Correct Go toolchain version

[ghost]

What type of PR is this?
Bug

Which issue does this PR fix:
N/A

What does this PR do / Why do we need it:
This corrects the issue below, from here:

As of Go 1.21, toolchain versions must use the 1.N.P syntax.

1.23 in go.mod does not match this syntax and there is no additional toolchain directive, which may cause some go commands to fail.

If an issue # is not available please add repro steps and logs from aws-gateway-controller showing the issue:
N/A

Testing done on this change:

Ran make e2e-test successfully.

Automation added to e2e:

N/A

Will this PR introduce any new dependencies?:

No.

Will this break upgrades or downgrades. Has updating a running cluster been tested?:
No.

Does this PR introduce any user-facing change?:

Set Go version to 1.23.6 to comply with CodeQL scans

Do all end-to-end tests successfully pass when running make e2e-test?:

Yes:

[SynchronizedAfterSuite] 
/Volumes/workplace/aws-application-networking-k8s/test/suites/integration/suite_test.go:72
{"level":"info","ts":"2025-02-10T12:38:33.562-0800","caller":"test/framework.go:266","msg":"Deleting objects: *v1.Gateway/test-gateway, *v1.Pod/grpc-runner"}
{"level":"info","ts":"2025-02-10T12:38:33.662-0800","caller":"test/framework.go:285","msg":"Waiting for NotFound, objects: *v1.Gateway/test-gateway, *v1.Pod/grpc-runner"}
[SynchronizedAfterSuite] PASSED [30.747 seconds]
------------------------------

Ran 69 of 69 Specs in 3068.433 seconds
SUCCESS! -- 69 Passed | 0 Failed | 0 Pending | 0 Skipped
--- PASS: TestIntegration (3068.43s)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[mikestvz]

🚢 LGTM