rebase: bump github.com/prometheus/client_golang from 1.15.1 to 1.16.0

Bumps [github.com/prometheus/client_golang](https://github.com/prometheus/client_golang) from 1.15.1 to 1.16.0.
- [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/v1.15.1...v1.16.0)

---
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/github.com/prometheus/procfs/mountstats.go

@@ -186,6 +186,8 @@ type NFSOperationStats struct {
 	CumulativeTotalResponseMilliseconds uint64
 	// Duration from when a request was enqueued to when it was completely handled.
 	CumulativeTotalRequestMilliseconds uint64
+	// The average time from the point the client sends RPC requests until it receives the response.
+	AverageRTTMilliseconds float64
 	// The count of operations that complete with tk_status < 0.  These statuses usually indicate error conditions.
 	Errors uint64
 }
@@ -534,7 +536,6 @@ func parseNFSOperationStats(s *bufio.Scanner) ([]NFSOperationStats, error) {
 
 			ns = append(ns, n)
 		}
-
 		opStats := NFSOperationStats{
 			Operation:                           strings.TrimSuffix(ss[0], ":"),
 			Requests:                            ns[0],
@@ -546,6 +547,9 @@ func parseNFSOperationStats(s *bufio.Scanner) ([]NFSOperationStats, error) {
 			CumulativeTotalResponseMilliseconds: ns[6],
 			CumulativeTotalRequestMilliseconds:  ns[7],
 		}
+		if ns[0] != 0 {
+			opStats.AverageRTTMilliseconds = float64(ns[6]) / float64(ns[0])
+		}
 
 		if len(ns) > 8 {
 			opStats.Errors = ns[8]