Bump python-prctl from 1.7 to 1.8.1

Bumps [python-prctl](https://github.com/seveas/python-prctl) from 1.7 to 1.8.1.
- [Release notes](https://github.com/seveas/python-prctl/releases)
- [Commits](seveas/python-prctl@v1.7...v1.8.1)

---
updated-dependencies:
- dependency-name: python-prctl
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements.txt

@@ -1,6 +1,6 @@
 riptide-lib >= 0.8.0b1, < 0.9
 tornado==6.3.2
 Click==7.0
-python-prctl==1.7; sys_platform == 'linux'
+python-prctl==1.8.1; sys_platform == 'linux'
 certauth==1.3.0
 guppy3==3.1.3