Bump boto3 from 1.12.0 to 1.12.5

Bumps [boto3](https://github.com/boto/boto3) from 1.12.0 to 1.12.5.
- [Release notes](https://github.com/boto/boto3/releases)
- [Changelog](https://github.com/boto/boto3/blob/develop/CHANGELOG.rst)
- [Commits](https://github.com/boto/boto3/compare/1.12.0...1.12.5)

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

requirements.txt

@@ -1,7 +1,7 @@
 PyYaml==5.3
 azure-common==1.1.24
 azure-mgmt-dns==3.0.0
-boto3==1.12.0
+boto3==1.12.5
 botocore==1.15.5
 dnspython==1.16.0
 docutils==0.16