chore: remove duplicates in coveragerc (#1511)

* chore: remove duplicates in coveragerc

* chore: fix formatting

Author: chandra-siri

.coveragerc

@@ -4,11 +4,7 @@ branch = True
 [report]
 show_missing = True
 omit =
-  .nox/*
-  .nox/*
-  .nox/*
-  .nox/*
-  .nox/*
+    .nox/*
     google/cloud/storage/__init__.py
     google/cloud/storage/gapic_version.py
 exclude_lines =