fix(deps): update module github.com/prometheus/client_golang to v1.21.1

Signed-off-by: red-hat-konflux <126015336+red-hat-konflux[bot]@users.noreply.github.com>

Author: red-hat-konflux[bot]

go.mod

@@ -8,7 +8,7 @@ require (
 	github.com/blang/semver/v4 v4.0.0
 	github.com/go-kit/log v0.2.1
 	github.com/lib/pq v1.10.9
-	github.com/prometheus/client_golang v1.17.0
+	github.com/prometheus/client_golang v1.21.1
 	github.com/prometheus/client_model v0.4.1-0.20230718164431-9a2bf3000d16
 	github.com/prometheus/common v0.44.0
 	github.com/prometheus/exporter-toolkit v0.10.0