BaseTools: Fix Python SyntaxWarning

- Windows paths must be escaped
- Regex should use raw strings

Signed-off-by: Tim Crawford <tcrawford@system76.com>

BaseTools/Source/Python/UPT/Library/CommentParsing.py

@@ -238,7 +238,7 @@ def ParseDecPcdGenericComment (GenericComment, ContainerFile, TokenSpaceGuidCNam
         #
         # To replace Macro
         #
-        MACRO_PATTERN = '[\t\s]*\$\([A-Z][_A-Z0-9]*\)'
+        MACRO_PATTERN = r'[\t\s]*\$\([A-Z][_A-Z0-9]*\)'
         MatchedStrs =  re.findall(MACRO_PATTERN, Comment)
         for MatchedStr in MatchedStrs:
             if MatchedStr: