ci(github): only trigger build when merging (#641)

.github/workflows/roller.yml

@@ -29,6 +29,25 @@ jobs:
     if: github.event.pull_request.draft == false
     runs-on: ubuntu-latest
     steps:
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: 1.19.x
+    - name: Checkout code
+      uses: actions/checkout@v2
+    - name: Test
+      run: |
+        go test -tags="mock_prover" -v -coverprofile=coverage.txt ./...
+    - name: Upload coverage reports to Codecov
+      uses: codecov/codecov-action@v3
+      env:
+        CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
+      with:
+        flags: roller
+  compile:
+    if: github.event_name == 'push' # will only be triggered when pushing to main & staging & develop & alpha
+    runs-on: ubuntu-latest
+    steps:
     - uses: actions-rs/toolchain@v1
       with:
         toolchain: nightly-2022-12-10
@@ -47,13 +66,6 @@ jobs:
     - name: Test
       run: |
         make roller
-        go test -tags="mock_prover" -v -coverprofile=coverage.txt ./...
-    - name: Upload coverage reports to Codecov
-      uses: codecov/codecov-action@v3
-      env:
-        CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
-      with:
-        flags: roller
   check:
     if: github.event.pull_request.draft == false
     runs-on: ubuntu-latest