Investigate `constraints` not being applied correctly by all managers

[jamietanna]

I.e. for https://github.com/JamieTanna-Mend-testing/test-any-updates

DEBUG: latest commit (repository=JamieTanna-Mend-testing/test-any-updates, branch=renovate/github.com-oapi-codegen-nullable-1.x)
       "branchName": "main",
       "latestCommitDate": "2026-04-13T17:12:01.000Z",
       "sha": "7f42f1932e90e89fce548c62b71ba0f67f2b1a19"
DEBUG: manager.getUpdatedPackageFiles() reuseExistingBranch=false (repository=JamieTanna-Mend-testing/test-any-updates, branch=renovate/github.com-oapi-codegen-nullable-1.x)
DEBUG: gomod.updateDependency: v1.1.0 (repository=JamieTanna-Mend-testing/test-any-updates, branch=renovate/github.com-oapi-codegen-nullable-1.x)
DEBUG: Updating github.com/oapi-codegen/nullable in go.mod (repository=JamieTanna-Mend-testing/test-any-updates, branch=renovate/github.com-oapi-codegen-nullable-1.x)
DEBUG: updateArtifacts for updatedPackageFiles (repository=JamieTanna-Mend-testing/test-any-updates, branch=renovate/github.com-oapi-codegen-nullable-1.x)
DEBUG: gomod.updateArtifacts(go.mod) (repository=JamieTanna-Mend-testing/test-any-updates, branch=renovate/github.com-oapi-codegen-nullable-1.x)
DEBUG: Using go version 1.26.1 found in toolchain directive (repository=JamieTanna-Mend-testing/test-any-updates, branch=renovate/github.com-oapi-codegen-nullable-1.x)
DEBUG: Setting CONTAINERBASE_CACHE_DIR to /tmp/renovate/cache/containerbase (repository=JamieTanna-Mend-testing/test-any-updates, branch=renovate/github.com-oapi-codegen-nullable-1.x)
DEBUG: Using containerbase dynamic installs (repository=JamieTanna-Mend-testing/test-any-updates, branch=renovate/github.com-oapi-codegen-nullable-1.x)
DEBUG: Executing command (repository=JamieTanna-Mend-testing/test-any-updates, branch=renovate/github.com-oapi-codegen-nullable-1.x)
       "command": "install-tool golang 1.26.1"

However:

{
  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
  "extends": [
    "config:best-practices"
  ],
  "constraints": {
    "golang": "1.23.0"
  }
}