Drop Swift 4.0

.swift-version

@@ -1 +1 @@
-4.0
+4.1

Sources/Base32/Base32.swift

@@ -224,18 +224,10 @@ private func base32encode(_ data: UnsafeRawPointer, _ length: Int, _ table: [Int
     
     // return
     if let base32Encoded = String(validatingUTF8: resultBuffer) {
-#if swift(>=4.1)
         resultBuffer.deallocate()
-#else
-        resultBuffer.deallocate(capacity: resultBufferSize)
-#endif
         return base32Encoded
     } else {
-#if swift(>=4.1)
         resultBuffer.deallocate()
-#else
-        resultBuffer.deallocate(capacity: resultBufferSize)
-#endif
         fatalError("internal error")
     }
 }