fix: case sensitivity for README.md in publishing

Author: Hugo Briand

MANIFEST.in

@@ -1,2 +1,2 @@
-include Readme.md
+include README.md
 include version.txt

setup.py

@@ -12,7 +12,7 @@ def version():
 
     # Try to parse tag from CI variable, if set write version.txt file with current version
     if ci_tag is not None:
-        if re.match('\d+(\.\d+)*', ci_tag):
+        if re.match(r'\d+(\.\d+)*', ci_tag):
             with open('version.txt', 'w+') as f:
                 f.write(ci_tag)
             return ci_tag