Use u64 instead of i64 in Int type (#11356)

## Summary

I believe the value here is always unsigned, since we represent `-42` as
a unary operator on `42`.

crates/ruff_python_parser/src/lexer.rs

@@ -1777,7 +1777,7 @@ def f(arg=%timeit a = b):
     #[test]
     fn test_numbers() {
         let source =
-            "0x2f 0o12 0b1101 0 123 123_45_67_890 0.2 1e+2 2.1e3 2j 2.2j 000 0x995DC9BBDF1939FA";
+            "0x2f 0o12 0b1101 0 123 123_45_67_890 0.2 1e+2 2.1e3 2j 2.2j 000 0x995DC9BBDF1939FA 0x995DC9BBDF1939FA995DC9BBDF1939FA";
         assert_debug_snapshot!(lex_source(source));
     }
 

crates/ruff_python_parser/src/snapshots/ruff_python_parser__lexer__tests__numbers.snap

@@ -79,12 +79,18 @@ expression: lex_source(source)
     ),
     (
         Int {
-            value: 0x995DC9BBDF1939FA,
+            value: 11051210869376104954,
         },
         64..82,
     ),
+    (
+        Int {
+            value: 0x995DC9BBDF1939FA995DC9BBDF1939FA,
+        },
+        83..117,
+    ),
     (
         Newline,
-        82..82,
+        117..117,
     ),
 ]