Bump selenium requirement. Forgotten in r19432.

Commit ready for merge.
 - Legacy-Id: 19505

Author: larseggert

requirements.txt

@@ -62,7 +62,7 @@ requests!=2.12.*
 requests-mock>=1.8
 rfc2html>=2.0.1
 scout-apm>=2.23.0
-selenium>=3.9.0
+selenium>=4.0.0
 six>=1.10.0
 svn>=1.0.1
 tblib>=1.3.0