chore(deps): Bump golang to 1.21.9

[periklis]

What this PR does / why we need it:
Addresses several CVEs:

• CVE-2023-45288 - net/http, x/net/http2: close connections when receiving too many headers (CVE-2023-45288) golang/go#65051 (fixed in Go 1.21.9)
• CVE-2024-24783 and Go issue https://go.dev/issue/65390. (fixed in Go 1.21.8)
• CVE-2023-45290 and Go issue https://go.dev/issue/65383. (fixed in Go 1.21.8)
• CVE-2023-45289 and Go issue https://go.dev/issue/65065. (fixed in Go 1.21.8)
• CVE-2024-24785 and Go issue https://go.dev/issue/65697. (fixed in Go 1.21.8)
• CVE-2024-24784 and Go issue https://go.dev/issue/65083. (fixed in Go 1.21.8 / Probably not affected)
• CVE-2023-39326 and Go issue https://go.dev/issue/64433. (fixed in Go 1.21.5)
• CVE-2023-45285 and Go issue https://go.dev/issue/63845. (fixed in Go 1.21.5 / Not affected)
• CVE-2023-45283 and Go issue https://go.dev/issue/64028. (fixed in Go 1.21.5 / Probably not affected)
• CVE-2023-45283 and Go issue https://go.dev/issue/63713. (fixed in Go 1.21.4 / Not affected)
• CVE-2023-45284 and Go issue https://go.dev/issue/63713. (fixed in Go 1.21.4 / Not affected)

Replaces:

• chore(deps): update module golang.org/x/net to v0.23.0 [security] (main) #12460 for CVE-2023-45288

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• CHANGELOG.md updated
  • If the change is worth mentioning in the release notes, add add-to-release-notes label
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• For Helm chart changes bump the Helm chart version in production/helm/loki/Chart.yaml and update production/helm/loki/CHANGELOG.md and production/helm/loki/README.md. Example PR
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[grafanabot]

Hello @periklis!
Backport pull requests need to be either:

• Pull requests which address bugs,
• Urgent fixes which need product approval, in order to get merged,
• Docs changes.

Please, if the current pull request addresses a bug fix, label it with the type/bug label.
If it already has the product approval, please add the product-approved label. For docs changes, please add the type/docs label.
If the pull request modifies CI behaviour, please add the type/ci label.
If none of the above applies, please consider removing the backport label and target the next major/minor release.
Thanks!