CI: Use sh in actions/setup-vtest/action.yml

Bash might not always be preinstalled and we don't make use of any
bash-specific features either. Switch to POSIX sh for simplicity.

This partly reverts the fix in 073240044e, which
installed `bash` for the musl job.

.github/actions/setup-vtest/action.yml

@@ -7,13 +7,13 @@ runs:
 
     - name: Setup coredumps
       if: ${{ startsWith(matrix.os, 'ubuntu-') }}
-      shell: bash
+      shell: sh
       run: |
         sudo sysctl -w fs.suid_dumpable=1
         sudo sysctl kernel.core_pattern=/tmp/core.%h.%e.%t
 
     - name: Setup ulimit for core dumps
-      shell: bash
+      shell: sh
       run: |
         # This is required for macOS which does not actually allow to increase
         # the '-n' soft limit to the hard limit, thus failing to run.
@@ -22,7 +22,7 @@ runs:
 
     - name: Get VTest latest commit SHA
       id: vtest-sha
-      shell: bash
+      shell: sh
       run: |
         echo "sha=$(git ls-remote https://code.vinyl-cache.org/vtest/VTest2 HEAD | cut -f1)" >> $GITHUB_OUTPUT
 
@@ -35,12 +35,12 @@ runs:
 
     - name: Install VTest
       if: ${{ steps.cache-vtest.outputs.cache-hit != 'true' }}
-      shell: bash
+      shell: sh
       run: |
         DESTDIR=${{ github.workspace }}/vtest scripts/build-vtest.sh
 
     - name: Install problem matcher for VTest
-      shell: bash
+      shell: sh
       # This allows one to more easily see which tests fail.
       run: echo "::add-matcher::.github/vtest.json"
 

.github/workflows/musl.yml

@@ -21,7 +21,7 @@ jobs:
           echo '/tmp/core/core.%h.%e.%t' > /proc/sys/kernel/core_pattern
       - uses: actions/checkout@v6
       - name: Install dependencies
-        run: apk add gcc gdb make bash tar git python3 libc-dev linux-headers pcre-dev pcre2-dev openssl-dev lua5.3-dev grep socat curl musl-dbg lua5.3-dbg jose
+        run: apk add gcc gdb make tar git python3 libc-dev linux-headers pcre-dev pcre2-dev openssl-dev lua5.3-dev grep socat curl musl-dbg lua5.3-dbg jose
       - uses: ./.github/actions/setup-vtest
       - name: Build
         run: make -j$(nproc) TARGET=linux-musl DEBUG="-DDEBUG_POOL_INTEGRITY -DDEBUG_UNIT" ARCH_FLAGS='-ggdb3' CC=cc V=1 USE_LUA=1 LUA_INC=/usr/include/lua5.3 LUA_LIB=/usr/lib/lua5.3 USE_OPENSSL=1 USE_PCRE2=1 USE_PCRE2_JIT=1 USE_PROMEX=1