exclude stringers.go files from code coverage (#119)

.codecov.yml

@@ -1,2 +1,4 @@
 ignore:
   - "examples/**"
+  - "**/stringers.go"
+  - "**/*_stringers.go"

.gitignore

@@ -3,9 +3,13 @@ go.work
 go.work.sum
 # Test binary, built with `go test -c`
 *.test
+# Test coverage profiles.
+profiles/
+
 # Dependency directories after running `go mod vendor`
 vendor/
 
+
 # Binaries for programs and plugins
 *.elf
 *.uf2