Update parking_lot requirement from 0.10 to 0.11

Updates the requirements on [parking_lot](https://github.com/Amanieu/parking_lot) to permit the latest version.
- [Release notes](https://github.com/Amanieu/parking_lot/releases)
- [Changelog](https://github.com/Amanieu/parking_lot/blob/master/CHANGELOG.md)
- [Commits](Amanieu/parking_lot@0.10.0...0.11.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

tokio-postgres/Cargo.toml

@@ -43,7 +43,7 @@ byteorder = "1.0"
 fallible-iterator = "0.2"
 futures = "0.3"
 log = "0.4"
-parking_lot = "0.10"
+parking_lot = "0.11"
 percent-encoding = "2.0"
 pin-project-lite = "0.1"
 phf = "0.8"