CC-2075: Update Gleam to 1.13

[andy1li]

CC-2075: Update Gleam to 1.13

---

Note

Updates Gleam from 1.11.x to 1.13.0 across docs/config and adds a gleam-1.13 Dockerfile/buildpack.

• Build/Infra:
  • Add dockerfiles/gleam-1.13.Dockerfile based on v1.13.0-erlang-alpine and cache deps/build.
  • Switch buildpack in compiled_starters/gleam/codecrafters.yml and solutions/gleam/01-at4/code/codecrafters.yml to gleam-1.13.
• Docs/Config:
  • Update required executable to gleam (1.13.0) in starter_templates/gleam/config.yml.
  • Update READMEs to require gleam (1.13.0).

^{Written by Cursor Bugbot for commit 23bb17a. This will update automatically on new commits. Configure here.}

[linear]

CC-2075 Update to Gleam version 1.13.0