[INFRA] remove buster from supported debian versions

Author: mautz-et-tong

.github/workflows/main.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        version: [ 'buster', 'bullseye', 'bookworm' ]
+        version: [ 'bullseye', 'bookworm' ]
     steps:
       - name: Checkout
         uses: actions/checkout@v4

.github/workflows/pull_request.yml

@@ -8,7 +8,7 @@ jobs:
   lint:
     strategy:
       matrix:
-        version: [ 'buster', 'bullseye', 'bookworm' ]
+        version: [ 'bullseye', 'bookworm' ]
     runs-on: ubuntu-latest
     container: pipelinecomponents/hadolint:latest
     steps:

.github/workflows/schedule.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        version: [ 'buster', 'bullseye', 'bookworm' ]
+        version: [ 'bullseye', 'bookworm' ]
     steps:
       - name: Checkout
         uses: actions/checkout@v4

README.md

@@ -1,6 +1,6 @@
 # PHP Base Image (WIP)
 
-This Repo contains the build instructions for the PHP base image (Stretch and Buster). All PHP images should inherit from this image.
+This Repo contains the build instructions for the PHP base image (bullseye and bookworm). All PHP images should inherit from this image.
 
 ## Documentation