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/net_softnet.go

@@ -76,6 +76,7 @@ func parseSoftnet(r io.Reader) ([]SoftnetStat, error) {
 	s := bufio.NewScanner(r)
 
 	var stats []SoftnetStat
+	cpuIndex := 0
 	for s.Scan() {
 		columns := strings.Fields(s.Text())
 		width := len(columns)
@@ -127,9 +128,13 @@ func parseSoftnet(r io.Reader) ([]SoftnetStat, error) {
 
 			softnetStat.SoftnetBacklogLen = us[0]
 			softnetStat.Index = us[1]
+		} else {
+			// For older kernels, create the Index based on the scan line number.
+			softnetStat.Index = uint32(cpuIndex)
 		}
 		softnetStat.Width = width
 		stats = append(stats, softnetStat)
+		cpuIndex++
 	}
 
 	return stats, nil