Bump tornado from 5.1.1 to 6.4.2 in /frameworks/Python/tornado

Bumps [tornado](https://github.com/tornadoweb/tornado) from 5.1.1 to 6.4.2.
- [Changelog](https://github.com/tornadoweb/tornado/blob/v6.4.2/docs/releases.rst)
- [Commits](tornadoweb/tornado@v5.1.1...v6.4.2)

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

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

Author: dependabot[bot]

frameworks/Python/tornado/requirements_py2_mongo.txt

@@ -1,3 +1,3 @@
-tornado==5.1.1
+tornado==6.4.2
 motor==2.0.0
 ujson==1.35

frameworks/Python/tornado/requirements_py2_pg.txt

@@ -1,3 +1,3 @@
-tornado==5.1.1
+tornado==6.4.2
 Momoko==2.2.4
 ujson==1.35

frameworks/Python/tornado/requirements_py3_mongo.txt

@@ -1,4 +1,4 @@
-tornado==6.0.2
+tornado==6.4.2
 motor==2.0.0
 uvloop==0.12.2
 ujson==1.35

frameworks/Python/tornado/requirements_py3_uvloop.txt

@@ -1,4 +1,4 @@
 asyncpg==0.21.0
-tornado==6.0.2
+tornado==6.4.2
 ujson==1.35
 uvloop==0.12.1