CC-2075: Update Gleam to 1.13

[andy1li]

CC-2075: Update Gleam to 1.13

---

Note

Upgrade Gleam to 1.13 across docs/configs and add a new 1.13 Dockerfile.

• Version Upgrade:
  • Bump required Gleam from 1.11.1 to 1.13.0 in compiled_starters/gleam/README.md, solutions/gleam/01-dr6/code/README.md, and starter_templates/gleam/config.yml.
  • Switch buildpack from gleam-1.11 to gleam-1.13 in compiled_starters/gleam/codecrafters.yml and solutions/gleam/01-dr6/code/codecrafters.yml.
• Docker:
  • Add dockerfiles/gleam-1.13.Dockerfile using base image ghcr.io/gleam-lang/gleam:v1.13.0-erlang-alpine, with dependency path env, build cache prep, and initial gleam build.

^{Written by Cursor Bugbot for commit 99b265e. This will update automatically on new commits. Configure here.}

[linear]

CC-2075 Update to Gleam version 1.13.0