Make plutus version detection more robust (#436)

Should address issue #426

Author: nielstron

pycardano/backend/blockfrost.py

@@ -174,7 +174,7 @@ def protocol_param(self) -> ProtocolParameters:
 
     def _get_script(self, script_hash: str) -> ScriptType:
         script_type = self.api.script(script_hash).type
-        if script_type.startswith("plutusV"):
+        if script_type.lower().startswith("plutusv"):
             ps = PlutusScript.from_version(
                 int(script_type[-1]),
                 bytes.fromhex(self.api.script_cbor(script_hash).cbor),