ci: retarget buildpack integration test to main instead of release version (#222)

Author: HKWinterhalter

.github/workflows/buildpack-integration-test.yml

@@ -11,7 +11,7 @@ permissions: read-all
 
 jobs:
   java11-buildpack-test:
-    uses: GoogleCloudPlatform/functions-framework-conformance/.github/workflows/buildpack-integration-test.yml@v1.8.0
+    uses: GoogleCloudPlatform/functions-framework-conformance/.github/workflows/buildpack-integration-test.yml@main
     with:
       http-builder-source: '/tmp/tests/conformance'
       http-builder-target: 'com.google.cloud.functions.conformance.HttpConformanceFunction'
@@ -20,7 +20,7 @@ jobs:
       prerun: 'invoker/conformance/prerun.sh'
       builder-runtime: 'java11'
   java17-buildpack-test:
-    uses: GoogleCloudPlatform/functions-framework-conformance/.github/workflows/buildpack-integration-test.yml@v1.8.0
+    uses: GoogleCloudPlatform/functions-framework-conformance/.github/workflows/buildpack-integration-test.yml@main
     with:
       http-builder-source: '/tmp/tests/conformance'
       http-builder-target: 'com.google.cloud.functions.conformance.HttpConformanceFunction'