Bump github.com/prometheus/client_golang from 1.14.0 to 1.15.1

Bumps [github.com/prometheus/client_golang](https://github.com/prometheus/client_golang) from 1.14.0 to 1.15.1.
- [Release notes](https://github.com/prometheus/client_golang/releases)
- [Changelog](https://github.com/prometheus/client_golang/blob/main/CHANGELOG.md)
- [Commits](https://github.com/prometheus/client_golang/compare/v1.14.0...v1.15.1)

---
updated-dependencies:
- dependency-name: github.com/prometheus/client_golang
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

vendor/google.golang.org/protobuf/internal/strs/strings_unsafe.go

@@ -87,7 +87,7 @@ func (sb *Builder) grow(n int) {
 	// Unlike strings.Builder, we do not need to copy over the contents
 	// of the old buffer since our builder provides no API for
 	// retrieving previously created strings.
-	sb.buf = make([]byte, 2*(cap(sb.buf)+n))
+	sb.buf = make([]byte, 0, 2*(cap(sb.buf)+n))
 }
 
 func (sb *Builder) last(n int) string {