chore(go): update go version to 1.23.6 and remove toolchain

Updates the Go version in go.mod to 1.23.6 and removes the toolchain 
line to simplify the module configuration. This ensures compatibility 
with the latest Go features and improvements.

.gitlab-ci.yml

@@ -61,6 +61,8 @@ check_release:
   image:
     name: goreleaser/goreleaser:v2.7.0@sha256:41247b711fc423eddcd8395b998b9de5c7d169bfe99e6a474ba35e87896c1343
     entrypoint: [ '' ]
+  variables:
+    GOTOOLCHAIN: auto
   script: |
     goreleaser check
     goreleaser release --snapshot --clean
@@ -77,6 +79,7 @@ release:
     # generate a changelog.
     GIT_DEPTH: 0
     GITLAB_TOKEN: $GITLAB_CI_TOKEN
+    GOTOOLCHAIN: auto
   # Only run this release job for tags, not every commit (for example).
   rules:
   - if: $CI_COMMIT_TAG

go.mod

@@ -1,8 +1,6 @@
 module gitlab.com/unboundsoftware/schemas
 
-go 1.22.5
-
-toolchain go1.23.6
+go 1.23.6
 
 require (
 	github.com/99designs/gqlgen v0.17.64