Remove prefixPeriod

Removed by swift-syntax in swiftlang/swift-syntax#1077.

Author: bnbarham

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -3321,7 +3321,7 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
         if case .postfixOperator? = token.previousToken(viewMode: .all)?.tokenKind { return true }
 
         switch token.nextToken(viewMode: .all)?.tokenKind {
-        case .prefixOperator?, .prefixPeriod?: return true
+        case .prefixOperator?, .period?: return true
         default: return false
         }
       }