ci: Also run benchmarks to make sure they do not become broken

As recent fixes show it is easy to break benchmarks while adjusting
tests without noticing. Prevent that to happen by running all benchmarks
just once during each CI run.

.github/workflows/ci.yml

@@ -37,3 +37,4 @@ jobs:
         fetch-depth: 0 # Make "git describe" work
 
     - run: go test
+    - run: go test -run ø -bench . -benchtime 1x