fix[venom]: fix unused variables pass (vyperlang#4259)

it corrupts the DFG. to see the bug before this commit, add another
`StoreEliminationPass` after `RemoveUnusedVariablesPass`.

this commit invalidates the DFG after removing unused variables.

vyper/venom/passes/remove_unused_variables.py

@@ -26,6 +26,7 @@ def run_pass(self):
             self._process_instruction(inst)
 
         self.analyses_cache.invalidate_analysis(LivenessAnalysis)
+        self.analyses_cache.invalidate_analysis(DFGAnalysis)
 
     def _process_instruction(self, inst):
         if inst.output is None: