ci: disable setup-beam problem matchers to quiet dep-warning annotations (#10)

## Summary

Closes #9 (partially - see caveat below).

- `erlef/setup-beam@v1` registers GitHub Actions problem matchers by
default (`disable_problem_matchers: false`), which scan mix/erlc
compiler output and promote matching lines into annotations. That's what
was turning postgrex/rewrite's deprecated `xref: [exclude: ...]` and
yamerl's deprecated `catch ...` syntax - both harmless compiler warnings
from third-party deps - into annotation clutter on every build.
- All three of those deps (`postgrex`, `rewrite`, `yamerl`) are already
at their latest published Hex versions (verified via `mix hex.outdated
--all`), so there's no version bump that fixes the underlying warnings -
they're upstream-only until those maintainers migrate. Setting
`disable_problem_matchers: true` on all three `erlef/setup-beam@v1`
steps (`ci.yaml`, both jobs in `burrito-release.yaml`) silences the
annotation promotion while leaving the actual compiler output visible in
the raw logs.

**Caveat**: the Node.js 20 deprecation annotation
(`mlugg/setup-zig@v2.2.1`) is *not* addressed by this PR - we're already
pinned to that action's latest release (`v2.2.1`), and its `action.yml`
still declares `using: 'node20'`. That's on the action's maintainer to
fix; nothing to change here until they bump it.

## Test plan

- [x] Validated both edited workflow YAML files parse correctly (`ruby
-ryaml`)
- [x] Confirmed via `mix hex.outdated --all` that
postgrex/rewrite/yamerl/yaml_elixir are all already at their latest
Hex-published versions - the warnings aren't from us being behind
- [x] Confirmed `mlugg/setup-zig`'s latest release (`v2.2.1`) still
targets `node20` in its own `action.yml` - not fixable by re-pinning
- [ ] Next real CI run on this branch should show 0 annotations from
setup-beam's matchers (xref + catch warnings gone), with only the Node20
one remaining

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

Author: bougyman

.github/workflows/burrito-release.yaml

@@ -34,6 +34,12 @@ jobs:
         with:
           otp-version: "29.0.3"
           elixir-version: "1.20.3"
+          # Without this, setup-beam's problem matchers promote every
+          # compiler warning from deps (e.g. postgrex/rewrite's deprecated
+          # `xref: [exclude: ...]`, yamerl's deprecated `catch ...` syntax -
+          # both already at their latest published Hex versions, so not
+          # fixable from here) into noisy GH Actions annotations. See #9.
+          disable_problem_matchers: true
       -
         # Version pinned to what Burrito 1.6.0 actually requires - its own
         # README says 0.15.2, but the version check enforces 0.16.0. See
@@ -67,6 +73,12 @@ jobs:
         with:
           otp-version: "29.0.3"
           elixir-version: "1.20.3"
+          # Without this, setup-beam's problem matchers promote every
+          # compiler warning from deps (e.g. postgrex/rewrite's deprecated
+          # `xref: [exclude: ...]`, yamerl's deprecated `catch ...` syntax -
+          # both already at their latest published Hex versions, so not
+          # fixable from here) into noisy GH Actions annotations. See #9.
+          disable_problem_matchers: true
       -
         # Same Burrito build as the `burrito` job above, so it needs the same
         # pinned Zig (see that job's comment) - missing here would fail this

.github/workflows/ci.yaml

@@ -21,6 +21,12 @@ jobs:
         with:
           otp-version: "29.0.3"
           elixir-version: "1.20.3"
+          # Without this, setup-beam's problem matchers promote every
+          # compiler warning from deps (e.g. postgrex/rewrite's deprecated
+          # `xref: [exclude: ...]`, yamerl's deprecated `catch ...` syntax -
+          # both already at their latest published Hex versions, so not
+          # fixable from here) into noisy GH Actions annotations. See #9.
+          disable_problem_matchers: true
       -
         name: Cache deps/build
         uses: actions/cache@v6