fix: suppress maturin tracing in Python test CI job

Maturin's _build_wheel parses stdout to find the wheel path, but with
RUST_LOG=info, maturin's pep517 tracing output goes to stdout and gets
parsed as the wheel filename, causing FileNotFoundError.

Adding maturin=warn to RUST_LOG suppresses the info-level log line that
breaks the wheel path detection.

Signed-off-by: Joe Isaacs <joe.isaacs@live.co.uk>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: joseph-isaacs

.github/workflows/ci.yml

@@ -81,7 +81,7 @@ jobs:
           || 'ubuntu-latest' }}
     timeout-minutes: 40
     env:
-      RUST_LOG: "info,uv=debug"
+      RUST_LOG: "info,maturin=warn,uv=debug"
       MATURIN_PEP517_ARGS: "--profile ci"
     steps:
       - uses: runs-on/action@v2