Add libwebp installation to coverage.yml workflow

The commit modifies the GitHub Actions workflow for code coverage testing. Specifically, it adds instructions to install libwebp to ensure necessary dependencies are met during the test coverage workflow execution. This prevents potential issues regarding missing libraries while running tests.

.github/workflows/coverage.yml

@@ -20,6 +20,9 @@ jobs:
         with:
           go-version: 1.22
 
+      - name: Install libwebp
+        run: sudo apt-get install libwebp-dev
+
       - name: Generate Test Coverage
         run: go test ./... -coverprofile=./cover.out