Bump restrictedpython from 5.0 to 6.1

Bumps [restrictedpython](https://github.com/zopefoundation/RestrictedPython) from 5.0 to 6.1.
- [Changelog](https://github.com/zopefoundation/RestrictedPython/blob/6.1/CHANGES.rst)
- [Commits](zopefoundation/RestrictedPython@5.0...6.1)

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

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

Author: dependabot[bot]

requirements.txt

@@ -79,7 +79,7 @@ PyYAML==5.3.1
 pyzmq==19.0.1
 qtconsole==4.7.5
 QtPy==1.9.0
-RestrictedPython==5.0
+RestrictedPython==6.1
 ruamel-yaml==0.15.80
 ruamel.yaml.clib==0.2.0
 scipy==1.4.1