Bump msrestazure from 0.6.3 to 0.6.4

Bumps [msrestazure](https://github.com/Azure/msrestazure-for-python) from 0.6.3 to 0.6.4.
- [Release notes](https://github.com/Azure/msrestazure-for-python/releases)
- [Commits](https://github.com/Azure/msrestazure-for-python/compare/v0.6.3...v0.6.4)

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

requirements.txt

@@ -12,7 +12,7 @@ google-cloud-core==1.3.0
 google-cloud-dns==0.32.0
 ipaddress==1.0.23
 jmespath==0.10.0
-msrestazure==0.6.3
+msrestazure==0.6.4
 natsort==6.2.1
 ns1-python==0.16.0
 ovh==0.5.0