fix(deps): bump supported Go versions to 1.24.3 and 1.23.9 (#496)

It's time to update Relay's supported Go versions, due to a recent
upstream Go release.

The Go major release cadence is ~every 6 months; the two most recent
major versions are supported.
Note that between major releases, the Go team often ships multiple minor
versions.


| | Current repo configuration | Desired repo configuration |

|-------------|------------------------------------|---------------------------------------------------------------------------------------------------------------------|
| Latest | 1.24.2 | [1.24.3](https://go.dev/doc/devel/release#go1.24.3)
|
| Penultimate | 1.23.8|
[1.23.9](https://go.dev/doc/devel/release#go1.23.9) |


This PR's change was generated by running:
```bash
./scripts/update-go-release-version.sh 1.24.3 1.23.9
```

- [ ] I have triggered CI on this PR (either close & reopen this PR in
Github UI, or `git commit -m "run ci" --allow-empty && git push`)

Co-authored-by: LaunchDarklyReleaseBot <[email protected]>

Author: github-actions[bot]

.github/variables/go-versions.env

@@ -1,2 +1,2 @@
-latest=1.24.2
-penultimate=1.23.8
+latest=1.24.3
+penultimate=1.23.9

Dockerfile

@@ -2,7 +2,7 @@
 
 # This is a standalone Dockerfile that does not depend on goreleaser building the binary
 # It is NOT the version that is pushed to dockerhub
-FROM golang:1.24.2-alpine3.21 as builder
+FROM golang:1.24.3-alpine3.21 as builder
 # See "Runtime platform versions" in CONTRIBUTING.md
 
 RUN apk --no-cache add \