Bump flask from 1.1.1 to 2.3.2

Bumps [flask](https://github.com/pallets/flask) from 1.1.1 to 2.3.2.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](https://github.com/pallets/flask/compare/1.1.1...2.3.2)

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

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

requirements.txt

@@ -3,7 +3,7 @@ lxml==4.6.3
 numpy==1.16.4
 wordcloud==1.5.0
 matplotlib==3.1.1
-Flask==1.1.1
+Flask==2.3.2
 Cython==0.29.13
 pyOpenSSL==19.0.0
 Pillow==8.1.1