chore: Bump version to 0.13.13 for next development cycle

[max-sixty]

Post-0.13.12 release version bump.

Generated by cargo release patch --no-publish --no-push --execute --no-verify --no-confirm --no-tag plus task prqlc:test-all to refresh version-bearing snapshots.

This was written by Claude Code on behalf of @max-sixty

[prql-bot]

The mdbook-prql package isn't covered by task prqlc:test-all, so its version-bearing snapshot wasn't refreshed. Running cargo test -p mdbook-prql --test documentation -- book::test_prql_examples_compile locally fails:

-    '0.13.12' AS version
+    '0.13.13' AS version

The fix is mechanical — bump the literal in web/book/tests/documentation/snapshots/documentation__book__project__target__version__1.snap from '0.13.12' to '0.13.13'. (For context, prql.version returns the compiler version, which is overridden in tests to CARGO_PKG_VERSION of mdbook-prql — now 0.13.13.) This was caught and updated in every recent bump PR (#5611, #5622, #5719) but missed here.

Separately, the docs example at web/book/src/project/target.md:86 still reads prql version:"0.13.12". This was bumped in #5611 / #5719 too — not test-breaking, just an out-of-date example.

Happy to push a commit with both fixes if useful.

[prql-bot]

CI shows two failures; only the first is substantive.

test-deps-min-versions — pre-existing, not caused by this PR but exposed by it. The Cargo.lock/Cargo.toml touches here trigger the nightly path filter (tests.yaml:110-116), so the nightly-only test-deps-min-versions job runs for the first time since #5834 merged. That PR loosened chrono from 0.4.44 to 0.4 in prqlc/prqlc/Cargo.toml:61; under cargo update -Z direct-minimal-versions, that resolves to chrono 0.4.0, but duckdb v1.10501.0 requires chrono ^0.4.22:

error: failed to select a version for `chrono`.
    ... required by package `duckdb v1.10501.0`
versions that meet the requirements `^0.4.22` are: 0.4.44, ..., 0.4.22
all possible versions conflict with previously selected packages.
  previously selected package `chrono v0.4.0`
    ... which satisfies dependency `chrono = "^0.4"` of package `prqlc v0.13.13`

Fix is to raise the floor in prqlc/prqlc/Cargo.toml from chrono = "0.4" to chrono = "0.4.22" (matches duckdb's transitive floor; still compatible with polars per #5834's rationale). The line is outside this PR's diff — happy to push the fix as a separate commit (or a separate PR if you'd prefer to keep this release-prep PR mechanical).

build-python-wheels (aarch64) — transient. Maturin tarball failed to extract (gzip: stdin: not in gzip format) during install — partial CDN download. Re-running the job should clear it. The x86_64 and macos universal2 wheel jobs were cancelled, not failed, so they'll re-run automatically when aarch64 is retried.