Bump plpygis from 0.2.1 to 0.5.5

Bumps [plpygis](https://github.com/bosth/plpygis) from 0.2.1 to 0.5.5.
- [Release notes](https://github.com/bosth/plpygis/releases)
- [Changelog](https://github.com/bosth/plpygis/blob/master/CHANGELOG.md)
- [Commits](bosth/plpygis@v0.2.1...v0.5.5)

---
updated-dependencies:
- dependency-name: plpygis
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

setup.py

@@ -22,7 +22,7 @@
           'pipelinewise-singer-python==1.*',
           'mysql-replication==0.43',
           'PyMySQL==1.1.*',
-          'plpygis==0.2.1',
+          'plpygis==0.5.5',
           'tzlocal==2.1',
       ],
       extras_require={