chore(deps): bump geoalchemy2 from 0.4.2 to 0.16.0

Bumps [geoalchemy2](https://github.com/geoalchemy/geoalchemy2) from 0.4.2 to 0.16.0.
- [Release notes](https://github.com/geoalchemy/geoalchemy2/releases)
- [Changelog](https://github.com/geoalchemy/geoalchemy2/blob/master/CHANGES.txt)
- [Commits](geoalchemy/geoalchemy2@0.4.2...0.16.0)

---
updated-dependencies:
- dependency-name: geoalchemy2
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements.txt

@@ -6,7 +6,7 @@ colander==2.0
 dogpile.cache==1.3.3
 elasticsearch==2.4.1
 elasticsearch_dsl==2.2.0
-geoalchemy2==0.4.2
+geoalchemy2==0.16.0
 geojson==3.1.0
 geomet==1.1.0
 kombu==5.4.1