Update api-digester with these SPI APIs

Author: Azoy

test/api-digester/stability-stdlib-abi-without-asserts.test

@@ -90,4 +90,11 @@ Func UnsafeMutableBufferPointer.withMemoryRebound(to:_:) has been removed
 Func UnsafeMutablePointer.withMemoryRebound(to:capacity:_:) has been removed
 Func UnsafePointer.withMemoryRebound(to:capacity:_:) has been removed
 
+// These APIs have been marked @_spi(_Unicode) and SPI is not part of our ABI.
+Struct Unicode._NFC is a new API without @available attribute
+Struct Unicode._NFD is a new API without @available attribute
+Struct Unicode._NormData is a new API without @available attribute
+Var StringProtocol._nfc is a new API without @available attribute
+Var StringProtocol._nfd is a new API without @available attribute
+
 // *** DO NOT DISABLE OR XFAIL THIS TEST. *** (See comment above.)