Adjust coverage options.

+ we don't need an exactly accurate count of the number of times each
  time ran. Remove -covermode, the default "set" will be fine to just
  track whether a given line ran at all.
+ add -benchtime=1x. We only need to run the benchmarks once.
+ -bench=. to match any character.

Signed-off-by: Denton Gentry <dgentry@tailscale.com>

.github/workflows/coverage.yml

@@ -29,7 +29,7 @@ jobs:
       run: go build ./cmd/...
 
     - name: Run tests on linux with coverage data
-      run: go test -race -covermode=atomic -coverprofile=coverage.txt -bench=regex ./...
+      run: go test -race -coverprofile=coverage.txt -bench=. -benchtime=1x ./...
 
     - name: coveralls.io
       uses: shogo82148/actions-goveralls@v1