sort package name in extras to make it reproducible

this fixes python-poetry/poetry#5125

Author: ali5h

src/poetry/core/packages/dependency.py

@@ -253,7 +253,7 @@ def base_pep_508_name(self) -> str:
         requirement = self.pretty_name
 
         if self.extras:
-            extras = ",".join(self.extras)
+            extras = ",".join(sorted(self.extras))
             requirement += f"[{extras}]"
 
         if isinstance(self.constraint, VersionUnion):