Bump ujson from 1.35 to 5.4.0 in /frameworks/Python/tornado

Bumps [ujson](https://github.com/ultrajson/ultrajson) from 1.35 to 5.4.0.
- [Release notes](https://github.com/ultrajson/ultrajson/releases)
- [Commits](ultrajson/ultrajson@v1.35...5.4.0)

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

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

Author: dependabot[bot]

frameworks/Python/tornado/requirements_py2_mongo.txt

@@ -1,3 +1,3 @@
 tornado==5.1.1
 motor==2.0.0
-ujson==1.35
+ujson==5.4.0

frameworks/Python/tornado/requirements_py2_pg.txt

@@ -1,3 +1,3 @@
 tornado==5.1.1
 Momoko==2.2.4
-ujson==1.35
+ujson==5.4.0

frameworks/Python/tornado/requirements_py3_mongo.txt

@@ -1,4 +1,4 @@
 tornado==6.0.2
 motor==2.0.0
 uvloop==0.12.2
-ujson==1.35
+ujson==5.4.0

frameworks/Python/tornado/requirements_py3_uvloop.txt

@@ -1,4 +1,4 @@
 asyncpg==0.21.0
 tornado==6.0.2
-ujson==1.35
+ujson==5.4.0
 uvloop==0.12.1