Updated solc-version detector test contract and fixed an issue where a [x,x) or (x,x] bound would allow x.

slither/detectors/attributes/old_solc.py

@@ -147,7 +147,7 @@ class OldSolc(AbstractDetector):
             :return: Returns True if the range can encapsulate any possible value, False if it is an invalid range.
             """
             return self.lower < self.upper or \
-                   (self.lower == self.upper and (self.lower_inclusive or self.upper_inclusive))
+                   (self.lower == self.upper and (self.lower_inclusive and self.upper_inclusive))
 
 
     @property

tests/old_solc.sol

@@ -1,4 +1,6 @@
-pragma solidity 0.4.21;
+// The version pragma below should get flagged by the detector
+// Reason: The expression "^0.4.0 >0.4.2" allows old solc (<0.4.23)
+pragma solidity ^0.5.22 || 0.4.23 - 0.4.24 || ^0.4.0 >0.4.2 || ~0.0.0    ^0.5.0 <= 0.5.50 || > 0.7.0;
 
 contract Contract{