Get rid of SwiftyJSON

it's not used anymore.

Mastodon.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -189,15 +189,6 @@
         "version" : "0.1.4"
       }
     },
-    {
-      "identity" : "swiftyjson",
-      "kind" : "remoteSourceControl",
-      "location" : "https://github.com/SwiftyJSON/SwiftyJSON.git",
-      "state" : {
-        "revision" : "b3dcd7dbd0d488e1a7077cb33b00f2083e382f07",
-        "version" : "5.0.1"
-      }
-    },
     {
       "identity" : "tabbarpager",
       "kind" : "remoteSourceControl",

MastodonSDK/Package.swift

@@ -40,7 +40,6 @@ let package = Package(
         .package(url: "https://github.com/MainasuK/CommonOSLog", from: "0.1.1"),
         .package(url: "https://github.com/MainasuK/FPSIndicator.git", from: "1.0.0"),
         .package(url: "https://github.com/slackhq/PanModal.git", from: "1.2.7"),
-        .package(url: "https://github.com/SwiftyJSON/SwiftyJSON.git", from: "5.0.0"),
         .package(url: "https://github.com/TimOliver/TOCropViewController.git", from: "2.6.1"),
         .package(url: "https://github.com/TwidereProject/MetaTextKit.git", exact: "2.2.5"),
         .package(url: "https://github.com/TwidereProject/TabBarPager.git", from: "0.1.0"),
@@ -103,7 +102,6 @@ let package = Package(
         .target(
             name: "MastodonSDK",
             dependencies: [
-                .product(name: "SwiftyJSON", package: "SwiftyJSON"),
                 .product(name: "NIOHTTP1", package: "swift-nio"),
             ]
         ),