chore: remove unnecessary coverage.out entry from .gitignore

Removed the specific `coverage.out` entry from `.gitignore` as it is unnecessary for the project.

.gitignore

@@ -154,7 +154,3 @@ playground/cloudfunction.zip
 # Ignore .test-infra/metrics/github_runs_prefetcher/code.zip
 # as its generated with terraform
 .test-infra/metrics/sync/github/github_runs_prefetcher/code.zip
-
-# Ignore ./sdks/go/pkg/beam/transforms/sql/coverage.out
-# as it is generated by running tests
-sdks/go/pkg/beam/transforms/sql/coverage.out