ci: pin Go 1.23 in the lint job to match golangci-lint v1.64.5

CI run 24932255728 had Verify and Test Coverage green but Lint failed
on 10 typecheck errors of the form:

    suite.Assert undefined (type *HttpSuiteTest has no field or method Assert)

The methods exist (testify's suite.Suite, embedded transitively), and
both `go build` and `go test ./...` resolve them fine. The failure is
exclusive to golangci-lint's bundled type-checker, which can't follow
methods promoted from external packages when the toolchain is newer
than the linter's build base.

golangci-lint v1.64.5 was built against Go 1.23. Pinning `go-version:
'1.23'` in the lint job aligns the typechecker with its own ABI. Verify
and Test Coverage stay on `stable` so production code is exercised
against the newest supported toolchain.

The pin is documented inline so a future bump of golangci-lint also
bumps the Go version in lockstep.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: insomnius

.github/workflows/general.yml

@@ -79,14 +79,20 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v5
         with:
-          go-version: stable
+          # golangci-lint v1.64.5 was built against Go 1.23. Pinning matches
+          # the linter's bundled type-checker version; using `stable` here
+          # makes typecheck fail to resolve methods promoted through embedded
+          # external types (e.g. testify's suite.Suite.Assert), even though
+          # `go build` and `go test` succeed against the same code.
+          go-version: '1.23'
           check-latest: true
           cache: true
 
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v6
         with:
           # Pin a recent stable release; bump with intent, not passively.
+          # When bumping the linter, also bump go-version above to match.
           version: v1.64.5
           args: --timeout=5m