Fix slither-check-erc output

This commit makes the `slither-check-erc` more relevant:
- when we confirm function interface's return type, we will now show it
  properly
- we had a mistake that we logged that the "value" is incorrect while we
  meant "type"

slither/tools/erc_conformance/erc/ercs.py

@@ -65,10 +65,10 @@ def _check_signature(erc_function, contract, ret):
     if function_return_type:
         function_return_type = ",".join([str(x) for x in function_return_type])
         if function_return_type == return_type:
-            txt = f"\t[✓] {sig} -> () (correct return value)"
+            txt = f"\t[✓] {sig} -> ({function_return_type}) (correct return type)"
             logger.info(txt)
         else:
-            txt = f"\t[ ] {sig} -> () should return {return_type}"
+            txt = f"\t[ ] {sig} -> ({function_return_type}) should return {return_type}"
             logger.info(txt)
 
             incorrect_return = output.Output(

tests/check-erc/test_1.txt

@@ -2,7 +2,7 @@
 
 ## Check functions
 [✓] totalSupply() is present
-	[✓] totalSupply() -> () (correct return value)
+	[✓] totalSupply() -> (uint256) (correct return type)
 	[✓] totalSupply() is view
 [ ] balanceOf(address) is missing 
 [ ] transfer(address,uint256) is missing