[Features] Don't enable ExistentialAny by default in Swift 6.

Author: hborla

include/swift/Basic/Features.def

@@ -116,12 +116,13 @@ SUPPRESSIBLE_LANGUAGE_FEATURE(RetroactiveAttribute, 364, "@retroactive", true)
 UPCOMING_FEATURE(ConciseMagicFile, 274, 6)
 UPCOMING_FEATURE(ForwardTrailingClosures, 286, 6)
 UPCOMING_FEATURE(BareSlashRegexLiterals, 354, 6)
-UPCOMING_FEATURE(ExistentialAny, 335, 6)
 UPCOMING_FEATURE(ImportObjcForwardDeclarations, 384, 6)
 UPCOMING_FEATURE(DisableOutwardActorInference, 401, 6)
 UPCOMING_FEATURE(InternalImportsByDefault, 409, 6)
 UPCOMING_FEATURE(FullTypedThrows, 413, 6)
 
+UPCOMING_FEATURE(ExistentialAny, 335, 7)
+
 EXPERIMENTAL_FEATURE(StaticAssert, false)
 EXPERIMENTAL_FEATURE(NamedOpaqueTypes, false)
 EXPERIMENTAL_FEATURE(FlowSensitiveConcurrencyCaptures, false)