fix(fstring): use two different tokens for x and X

src/core/format_spec/lexer.py

@@ -95,8 +95,10 @@ class FormatSpecLexer:
                 self.add_token(TokenType.T_DEC)
             case "o":
                 self.add_token(TokenType.T_OCT)
-            case "x" | "X":
+            case "x":
                 self.add_token(TokenType.T_HEX)
+            case "X":
+                self.add_token(TokenType.T_HEX_CAPS)
             case "e":
                 self.add_token(TokenType.T_SCI)
             case "f":

src/core/format_spec/parser.py

@@ -14,6 +14,7 @@ class FormatSpecParser:
         TokenType.T_DEC,
         TokenType.T_OCT,
         TokenType.T_HEX,
+        TokenType.T_HEX_CAPS,
         TokenType.T_SCI,
         TokenType.T_FIX,
         TokenType.T_PCT,

src/core/format_spec/token.py

@@ -24,6 +24,7 @@ class TokenType(Enum):
     T_DEC = auto()
     T_OCT = auto()
     T_HEX = auto()
+    T_HEX_CAPS = auto()
 
     ## Float
     T_SCI = auto()