marksthe BumpPtrAllocator class as @_spi(BumpPtrAllocator) instead of @_spi(RawSyntax)

Author: ChiduAnush

Sources/SwiftSyntax/BumpPtrAllocator.swift

@@ -13,7 +13,7 @@
 /// A ``BumpPtrAllocator`` that allocates `slabSize` at a time.
 /// Once all memory in a slab has been used, it allocates a new slab and no
 /// memory allocations are necessary until that slab is completely filled up.
-@_spi(RawSyntax) @_spi(Testing)
+@_spi(BumpPtrAllocator) @_spi(Testing)
 public class BumpPtrAllocator {
   typealias Slab = UnsafeMutableRawBufferPointer