chore: bump pg-core 0.6.0 → 0.6.1

[dobby-coder]

Bumps pg-core from 0.6.0 to 0.6.1 (patch).

Closes #163.

Skipped from the scan

• rand dev-dep 0.8.6 → 0.10.1: not applied. The rand08 dev-dep is pinned to 0.8 on purpose — pg_core::test::TestSetup/Sealer requires the rand 0.8 RNG trait. Bumping it to 0.10 would break the integration test harness (see Cargo.toml comment above rand08). Main rand = "0.10.0" is already current.
• RUSTSEC-2025-0134 (rustls-pemfile unmaintained): transitive with no fix path right now; not addressed here.

Verification

• cargo build ✅
• cargo test ✅ (87 passed)
• cargo clippy --all-targets ✅ (no warnings)
• cargo fmt --all -- --check ✅

Reviewer quickstart

git fetch origin && git checkout chore/bump-pg-core-0.6.1 && cargo test

[dobby-coder]

Reviewed (note: same bot identity opened the PR, so cannot self-approve).

Patch bump pg-core 0.6.0 → 0.6.1, plus transitive lockfile updates (windows-sys, socket2). CI is green across build (amd64/arm64), clippy, fmt, and tests. Dev-dep is bumped in lockstep so the integration test harness still resolves. The PR description correctly explains why the rand 0.8 dev-dep and the rustls-pemfile advisory are out of scope. LGTM — safe to merge from this agent's perspective.