do import only in function

mythril/laser/ethereum/plugins/plugin_factory.py

@@ -1,8 +1,4 @@
 from mythril.laser.ethereum.plugins.plugin import LaserPlugin
-from mythril.laser.ethereum.plugins.implementations.benchmark import BenchmarkPlugin
-from mythril.laser.ethereum.plugins.implementations.mutation_pruner import (
-    MutationPruner,
-)
 
 
 class PluginFactory:
@@ -11,9 +7,13 @@ class PluginFactory:
     @staticmethod
     def build_benchmark_plugin(name: str) -> LaserPlugin:
         """ Creates an instance of the benchmark plugin with the given name """
+        from mythril.laser.ethereum.plugins.implementations.benchmark import BenchmarkPlugin
         return BenchmarkPlugin(name)
 
     @staticmethod
     def build_mutation_pruner_plugin() -> LaserPlugin:
         """ Creates an instance of the mutation pruner plugin"""
+        from mythril.laser.ethereum.plugins.implementations.mutation_pruner import (
+            MutationPruner,
+        )
         return MutationPruner()