attempt to fix flaky "go fmt" ci check

.github/workflows/ci.yml

@@ -58,7 +58,7 @@ jobs:
 
     - name: go fmt
       if: matrix.os == 'macos-latest'
-      run: make fmt-go && git diff-index --quiet HEAD --
+      run: make fmt-go
 
     - name: npm ci
       run: cd scripts && npm ci

Makefile

@@ -32,12 +32,7 @@ vet-go:
 	go vet ./cmd/... ./internal/... ./pkg/...
 
 fmt-go:
-	# This uses "|| true" to swallow errors because for some reason this command
-	# started randomly failing when run inside GitHub Actions. It still formats
-	# all files successfully but then sometimes exits with a status of 1 (this
-	# started on April 14th, 2021). I don't know why this happens and don't know
-	# how to fix it. I'm just swallowing this error for now to move past this.
-	go fmt ./cmd/... ./internal/... ./pkg/... || true
+	test -z "$(shell go fmt ./cmd/... ./internal/... ./pkg/... )"
 
 no-filepath:
 	@! grep --color --include '*.go' -r '"path/filepath"' cmd internal pkg || ( \