Bump pyyaml from 4.2b1 to 5.1.2 in /api/src/main/resources

Bumps [pyyaml](https://github.com/yaml/pyyaml) from 4.2b1 to 5.1.2.
- [Release notes](https://github.com/yaml/pyyaml/releases)
- [Changelog](https://github.com/yaml/pyyaml/blob/master/CHANGES)
- [Commits](https://github.com/yaml/pyyaml/commits/5.1.2)

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

Author: dependabot[bot]

api/src/main/resources/requirements.txt

@@ -13,7 +13,7 @@ pyasn1==0.1.9
 pycparser==2.17
 pyhs2==0.6.0
 pywebhdfs==0.4.1
-pyyaml==4.2b1
+pyyaml==5.1.2
 requests==2.22.0
 sasl==0.2.1
 singledispatch==3.4.0.3