.github: control defconfig using pull request labels

Issue #597

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

.github/workflows/build.yml

@@ -2,6 +2,7 @@ name: Bob the Builder
 
 on:
   pull_request:
+    types: [opened, synchronize, reopened, labeled]
   push:
     branches:
       - main
@@ -37,6 +38,9 @@ jobs:
           else
               flavor=""
           fi
+          if ${{ contains(github.event.pull_request.labels.*.name, 'ci:main') }}; then
+              flavor=""
+          fi
           target=${{ matrix.target }}
           echo "dir=infix-$target"        >> $GITHUB_OUTPUT
           echo "tgz=infix-$target.tar.gz" >> $GITHUB_OUTPUT