Update quinn-proto to 0.11.15 and add lockfile regression test

[multiplex55]

Motivation

• Close a known vulnerability by upgrading the transitive quinn-proto lockfile entry to a patched 0.11.x release and prevent regressions with an automated test.

Description

• Updated Cargo.lock to move quinn-proto from 0.11.14 to 0.11.15 and recorded the new Cargo checksum generated by cargo update -p quinn-proto --precise 0.11.15 without adding a direct quinn-proto dependency in Cargo.toml.
• Preserved the existing reqwest -> quinn -> quinn-proto transitive relationship and did not alter reqwest or quinn declarations.
• Added tests/dependency_security.rs, a lockfile regression test that reads the workspace Cargo.lock via env!("CARGO_MANIFEST_DIR"), finds exact [[package]] records named quinn-proto, parses strict major.minor.patch numeric versions, requires at least one record, and enforces the secure range >= 0.11.15 and < 0.12.0.
• Included focused unit cases in the test for rejecting 0.11.14, accepting 0.11.15 and later 0.11.x patches, rejecting malformed/pre-release values, and rejecting an unexpected major/minor bump to 0.12.x.

Testing

• Ran cargo update -p quinn-proto --precise 0.11.15, which completed successfully and updated Cargo.lock with the new checksum.
• Compiled and executed the new test directly with rustc (CARGO_MANIFEST_DIR="$PWD" rustc --edition=2024 --test tests/dependency_security.rs -o /tmp/dependency_security_test && /tmp/dependency_security_test) and observed both tests passing (2 passed).
• Attempting cargo test --locked --test dependency_security and cargo build --locked --all-targets in the CI-like environment was blocked by missing system ALSA development metadata required by alsa-sys (build failure), preventing a full workspace run; the regression test itself passed when run standalone.
• cargo tree -i quinn-proto --locked reported no second vulnerable quinn-proto version in the active resolution for the tested targets, and cargo nextest could not be executed in the environment because cargo-nextest was not installed.

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Codex Task