ci: add conformance suite version override options

Author: panva

.github/workflows/conformance.yml

@@ -10,10 +10,17 @@ on:
   schedule:
     - cron: '47 11 * * 1'
   workflow_dispatch:
+    inputs:
+      conformance_suite_version:
+        description: 'Conformance Suite version override, e.g. release-v5.1.39 (takes precedence over vars.CONFORMANCE_SUITE_VERSION)'
+        required: false
+        type: string
 
 jobs:
   build:
     uses: panva/.github/.github/workflows/build-conformance-suite.yml@main
+    with:
+      version: ${{ inputs.conformance_suite_version || vars.CONFORMANCE_SUITE_VERSION || '' }}
 
   run:
     runs-on: ubuntu-latest