ci : use mirrors.kernel.org for Ubuntu packages (#3220)

This commit updates the ubuntu jobs to use mirrors sites instead of archive.ubuntu.com.

The motivation of this is an attempt to make the CI build more stable and avoid errors like:
https://github.com/ggml-org/whisper.cpp/actions/runs/15384056535/job/43291948394?pr=3217

.github/workflows/build.yml

@@ -101,6 +101,10 @@ jobs:
             -v ${{ github.workspace }}:/workspace \
             -w /workspace ${{ env.ubuntu_image }} /bin/sh -c '
             set -e
+            export DEBIAN_FRONTEND=noninteractive
+            sed -i "s|archive.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+            sed -i "s|security.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+
             apt update
             apt install -y build-essential libsdl2-dev cmake git
             cmake -B build
@@ -129,6 +133,10 @@ jobs:
             -v ${{ github.workspace }}:/workspace \
             -w /workspace ${{ env.ubuntu_image }} /bin/sh -c '
             set -e
+            export DEBIAN_FRONTEND=noninteractive
+            sed -i "s|archive.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+            sed -i "s|security.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+
             apt update
             apt install -y build-essential libsdl2-dev cmake git
             cmake -B build -DGGML_NATIVE=OFF -DGGML_CPU_ARM_ARCH=armv8-a
@@ -157,6 +165,10 @@ jobs:
             -v ${{ github.workspace }}:/workspace \
             -w /workspace ${{ env.ubuntu_image }} /bin/sh -c '
             set -e
+            export DEBIAN_FRONTEND=noninteractive
+            sed -i "s|archive.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+            sed -i "s|security.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+
             apt update
             apt install -y build-essential libsdl2-dev cmake git
             cmake -B build -DGGML_NATIVE=OFF -DGGML_CPU_ARM_ARCH=armv7-a+fp
@@ -242,6 +254,10 @@ jobs:
             -v ${{ github.workspace }}:/workspace \
             -w /workspace ${{ env.ubuntu_image }} /bin/sh -c '
             set -e
+            export DEBIAN_FRONTEND=noninteractive
+            sed -i "s|archive.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+            sed -i "s|security.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+
             apt update
             apt install -y build-essential cmake libsdl2-dev git
             cmake . -DWHISPER_SDL2=ON -DCMAKE_BUILD_TYPE=${{ matrix.build }}
@@ -272,6 +288,10 @@ jobs:
             -v ${{ github.workspace }}:/workspace \
             -w /workspace ${{ env.ubuntu_image }} /bin/sh -c '
             set -e
+            export DEBIAN_FRONTEND=noninteractive
+            sed -i "s|archive.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+            sed -i "s|security.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+
             apt update
             apt install -y build-essential cmake libsdl2-dev git
             cmake . -DWHISPER_SDL2=ON -DCMAKE_BUILD_TYPE=${{ matrix.build }} -DGGML_NATIVE=OFF -DGGML_CPU_ARM_ARCH=armv8-a
@@ -302,6 +322,10 @@ jobs:
             -v ${{ github.workspace }}:/workspace \
             -w /workspace ${{ env.ubuntu_image }} /bin/sh -c '
             set -e
+            export DEBIAN_FRONTEND=noninteractive
+            sed -i "s|archive.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+            sed -i "s|security.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+
             apt update
             apt install -y build-essential cmake libsdl2-dev git
             cmake . -DWHISPER_SDL2=ON -DCMAKE_BUILD_TYPE=${{ matrix.build }} -DGGML_NATIVE=OFF -DGGML_CPU_ARM_ARCH=armv7-a+fp
@@ -335,6 +359,10 @@ jobs:
             -v ${{ github.workspace }}:/workspace \
             -w /workspace ${{ env.ubuntu_image }} /bin/sh -c '
             set -e
+            export DEBIAN_FRONTEND=noninteractive
+            sed -i "s|archive.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+            sed -i "s|security.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+
             apt update
             apt install -y clang build-essential cmake libsdl2-dev git
             cmake . -DWHISPER_SDL2=ON -DCMAKE_BUILD_TYPE=${{ matrix.build }} -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_C_COMPILER=clang
@@ -365,6 +393,10 @@ jobs:
             -v ${{ github.workspace }}:/workspace \
             -w /workspace ${{ env.ubuntu_image }} /bin/sh -c '
             set -e
+            export DEBIAN_FRONTEND=noninteractive
+            sed -i "s|archive.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+            sed -i "s|security.ubuntu.com|mirrors.kernel.org|g" /etc/apt/sources.list
+
             apt update
             apt install -y build-essential cmake git
             cmake . -DCMAKE_BUILD_TYPE=Debug \