Update tornado requirement from >=6.0.3,~=6.0 to ~=6.4

Updates the requirements on [tornado](https://github.com/tornadoweb/tornado) to permit the latest version.
- [Changelog](https://github.com/tornadoweb/tornado/blob/master/docs/releases.rst)
- [Commits](tornadoweb/tornado@v6.0.3...v6.4.0)

---
updated-dependencies:
- dependency-name: tornado
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements.txt

@@ -1,4 +1,4 @@
-tornado~=6.0, >=6.0.3
+tornado~=6.5
 ovos_bus_client>=0.0.7,<2.0.0
 ovos-utils>=0.0.37,<1.0.0
 ovos-config>=0.0.12,<3.0.0