Use i32 comparision instead of char

Author: Agent-Hellboy

src/runtime/lpython_builtin.py

@@ -768,9 +768,10 @@ def _lpython_str_upper(x: str) -> str:
 def _lpython_str_isalpha(s: str) -> bool:
     char: str
     for char in s:
-        if 'a' <= char and char <= 'z':
+        char_ord: i32 = ord(char)
+        if 65 <= char_ord and char_ord <= 90:
             continue
-        if 'A' <= char and char <= 'Z':
+        if 97 <= char_ord and char_ord <= 122:
             continue
         return False
     return True
@@ -781,13 +782,14 @@ def _lpython_str_title(s: str) -> str:
     capitalize_next: bool = True
     char: str
     for char in s:
-        if char >= 'a' and char <= 'z':
+        char_ord: i32 = ord(char)
+        if char_ord >= 97  and char_ord <= 122:
             if capitalize_next:
                 result += chr(ord(char) - ord('a') + ord('A'))
                 capitalize_next = False
             else:
                 result += char
-        elif char >= 'A' and char <= 'Z':
+        elif char_ord >= 65 and char_ord <= 90:
             if capitalize_next:
                 result += char
                 capitalize_next = False