Bump to 4.0.0

Converting list_all_prs is a breaking change so requires a version bump

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "simple_ado"
-version = "3.18.0"
+version = "4.0.0"
 description = "A simple wrapper around the Azure DevOps REST API"
 
 license = "MIT"