deps: update dependency pip to v26 [security]

Author: renovate[bot]

requirements-dev.txt

@@ -69,7 +69,7 @@ pathspec==0.12.1
     # via
     #   black
     #   mypy
-pip==25.2
+pip==26.1
     # via pip-tools
 pip-tools==7.5.0
     # via -r requirements-dev.in