Merge pull request #642 from rxwei/dev/rxwei/string-processing-swift-main

Update string processing to swift/main

Author: shahmishal

common.py

@@ -50,7 +50,7 @@
         'swift-collections': '1.0.1',
         'swift-numerics': '1.0.1',
         'swift-system': '1.1.1',
-        'swift-experimental-string-processing': 'dev/8',
+        'swift-experimental-string-processing': 'swift/main',
     },
     'release/5.6': {
         'llvm-project': 'swift/release/5.6',