Fix some edge-case bugs around improper use of isinstance() (#405)

These all stem from the fact that `True == 1` and `isinstance(False, int)`

pyi.py

@@ -1433,7 +1433,7 @@ def _check_subscript_version_check(self, node: ast.Compare) -> None:
             slc = version_info.slice
             if isinstance(slc, ast.Constant):
                 # anything other than the integer 0 doesn't make much sense
-                if isinstance(slc.value, int) and slc.value == 0:
+                if type(slc.value) is int and slc.value == 0:
                     must_be_single = True
                 else:
                     self.error(node, Y003)
@@ -1445,7 +1445,7 @@ def _check_subscript_version_check(self, node: ast.Compare) -> None:
                 elif (
                     # allow only [:1] and [:2]
                     isinstance(slc.upper, ast.Constant)
-                    and isinstance(slc.upper.value, int)
+                    and type(slc.upper.value) is int
                     and slc.upper.value in {1, 2}
                 ):
                     can_have_strict_equals = slc.upper.value
@@ -1471,8 +1471,9 @@ def _check_version_check(
     ) -> None:
         comparator = node.comparators[0]
         if must_be_single:
-            if not isinstance(comparator, ast.Constant) or not isinstance(
-                comparator.value, int
+            if (
+                not isinstance(comparator, ast.Constant)
+                or type(comparator.value) is not int
             ):
                 self.error(node, Y003)
         elif not isinstance(comparator, ast.Tuple):

tests/sysversioninfo.pyi

@@ -1,14 +1,18 @@
 import sys
 
 if sys.version_info[0] == 2: ...
+if sys.version_info[0] == True: ...  # Y003 Unrecognized sys.version_info check  # E712 comparison to True should be 'if cond is True:' or 'if cond:'
 if sys.version_info[0.0] == 2: ...  # Y003 Unrecognized sys.version_info check
+if sys.version_info[False] == 2: ...  # Y003 Unrecognized sys.version_info check
 if sys.version_info[0j] == 2: ...  # Y003 Unrecognized sys.version_info check
 if sys.version_info[0] == (2, 7): ...  # Y003 Unrecognized sys.version_info check
 if sys.version_info[0] == '2': ...  # Y003 Unrecognized sys.version_info check
 if sys.version_info[1:] >= (7, 11): ...  # Y003 Unrecognized sys.version_info check
 if sys.version_info[::-1] < (11, 7): ...  # Y003 Unrecognized sys.version_info check
 if sys.version_info[:3] >= (2, 7): ...  # Y003 Unrecognized sys.version_info check
+if sys.version_info[:True] >= (2, 7): ...  # Y003 Unrecognized sys.version_info check
 if sys.version_info[:1] == (2,): ...
+if sys.version_info[:1] == (True,): ...  # Y003 Unrecognized sys.version_info check
 if sys.version_info[:1] == (2, 7): ...  # Y005 Version comparison must be against a length-1 tuple
 if sys.version_info[:2] == (2, 7): ...
 if sys.version_info[:2] == (2,): ...  # Y005 Version comparison must be against a length-2 tuple