Run cov on master branch only

Signed-off-by: Florian Hopfensperger <f.hopfensperger@gmail.com>

.github/workflows/go.yml

@@ -41,18 +41,21 @@ jobs:
         run: go test -v ./... -covermode=count -coverprofile=coverage.out
 
       - name: Convert coverage to lcov
+        if: startsWith(github.ref, 'refs/master')
         uses: jandelgado/gcov2lcov-action@v1.0.0
         with:
           infile: coverage.out
           outfile: coverage.lcov
 
       - name: Upload coverages
+        if: startsWith(github.ref, 'refs/master')
         uses: coverallsapp/github-action@v1.0.1
         with:
           github-token: ${{ secrets.github_token }}
           path-to-lcov: coverage.lcov
 
       - name: Trigger Go Report Card
+        if: startsWith(github.ref, 'refs/master')
         run: curl -d "repo=github.com/fhopfensperger/json-log-to-human-readable" https://goreportcard.com/checks
 
       - name: Clean directory