Bump numpy from 1.17.2 to 1.22.0 in /backend

Bumps [numpy](https://github.com/numpy/numpy) from 1.17.2 to 1.22.0.
- [Release notes](https://github.com/numpy/numpy/releases)
- [Changelog](https://github.com/numpy/numpy/blob/main/doc/HOWTO_RELEASE.rst)
- [Commits](numpy/numpy@v1.17.2...v1.22.0)

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

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

Author: dependabot[bot]

backend/requirements.txt

@@ -7,5 +7,5 @@ django-filter==2.2.0
 gunicorn==19.9.0
 django-rest-swagger==2.2.0
 xhtml2pdf==0.2.4
-numpy==1.17.2
+numpy==1.22.0
 pandas==0.25.1