ci: skip build if Bicep file unchanged (#17)

* ci: skip build if Bicep file unchanged

* chore: add whitespace to increase readability

.github/workflows/build.yml

@@ -22,13 +22,22 @@ jobs:
         id: build
         shell: bash {0} # Required to check exit code
         run: |
+          git diff --exit-code "$BICEP_FILE_PATH"
+          exit_code="$?"
+          if [[ "$exit_code" == 0 ]]; then
+            echo "No changes made to Bicep file. Skipping build."
+            exit "$exit_code"
+          fi
+
           az bicep build --file "$BICEP_FILE_PATH" --outfile "$OUTPUT_FILE_PATH"
           exit_code="$?"
           if [[ "$exit_code" != 0 ]]; then
             exit "$exit_code"
           fi
+
           git diff --exit-code "$OUTPUT_FILE_PATH"
           exit_code="$?"
+
           echo "exit-code=$exit_code" >> "$GITHUB_OUTPUT"
 
       - name: Push commit