fix: docs/requirements.txt to reduce vulnerabilities (#158)

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-PYLINT-609883

Co-authored-by: snyk-bot <[email protected]>

Author: meghasfdc

docs/requirements.txt

@@ -52,7 +52,7 @@ pbr==5.5.1
 pluggy==0.13.1
 policy-sentry==0.11.2
 py==1.10.0
-pylint==2.6.0
+pylint==2.6.1
 pyparsing==2.4.7
 pytest==6.2.1
 python-dateutil==2.8.1