Bump boto3 from 1.11.13 to 1.12.0

Bumps [boto3](https://github.com/boto/boto3) from 1.11.13 to 1.12.0.
- [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/1.11.13...1.12.0)

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==1.11.13
+boto3==1.12.0
 botocore==1.14.13
 dnspython==1.16.0
 docutils==0.16