updating language_version_explicit for version 4.2.1

Author: najacque

test/Parse/ConditionalCompilation/language_version_explicit.swift

@@ -22,15 +22,15 @@
 #endif
 
 // NOTE: Please modify this condition...
-#if swift(>=4.2)
+#if swift(>=4.2.1)
   let b = 1
 #else
   // This shouldn't emit any diagnostics.
   asdf asdf asdf asdf
 #endif
 
 // NOTE: ...and modify this condition...
-#if swift(>=4.2.1)
+#if swift(>=4.2.2)
   // This shouldn't emit any diagnostics.
   asdf asdf asdf asdf
 #else