feat(ci): publish both builder images

Author: t3hmrman

.github/workflows/ci-builder-image.yml

@@ -4,6 +4,8 @@ description: |
   Build (and push) the CI builder image
 
 on:
+  pull_request:
+
   workflow_dispatch:
     inputs:
       cargo-pgrx-version:
@@ -21,11 +23,16 @@ permissions:
   contents: none
 
 jobs:
-  build-and-push-builder-image:
+  builder-image:
     runs-on: ubuntu-latest
     permissions:
       contents: read
       packages: write
+    strategy:
+      matrix:
+        libc:
+          - gnu
+          - musl
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - uses: extractions/setup-just@e33e0265a09d6d736e2ee1e0eb685ef1de4669ff # v3
@@ -39,10 +46,13 @@ jobs:
 
       - name: Build builder image
         env:
+          BUILDER_TYPE: ${{ matrix.libc }}
           BUILDER_IMAGE_ARG_CARGO_PGRX_VERSION: ${{ inputs.cargo-pgrx-version || '0.12.5' }}
         run: |
           just build-builder-image
 
       - name: Push builder image
+        env:
+          BUILDER_TYPE: ${{ matrix.libc }}
         run: |
           just push-builder-image