Fix code block truncation (gonzalezreal#256)

* Fix unexpected code block truncation

* Remove unused code

* Update SnapshotTesting package

Author: gonzalezreal

Examples/Demo/Demo/ContentView.swift

@@ -100,16 +100,6 @@ struct ContentView: View {
   }
 }
 
-extension HorizontalAlignment {
-  private struct RowTitleAlignment: AlignmentID {
-    static func defaultValue(in context: ViewDimensions) -> CGFloat {
-      context[HorizontalAlignment.leading]
-    }
-  }
-
-  static let rowTitleAligmentGuide = HorizontalAlignment(RowTitleAlignment.self)
-}
-
 struct ContentView_Previews: PreviewProvider {
   static var previews: some View {
     ContentView()

Package.resolved

@@ -84,6 +84,7 @@ extension Theme {
     .codeBlock { configuration in
       ScrollView(.horizontal) {
         configuration.label
+          .fixedSize(horizontal: false, vertical: true)
           .relativeLineSpacing(.em(0.15))
           .relativePadding(.leading, length: .rem(1))
           .markdownTextStyle {

Sources/MarkdownUI/Theme/Theme+Basic.swift

@@ -96,6 +96,7 @@ extension Theme {
     .codeBlock { configuration in
       ScrollView(.horizontal) {
         configuration.label
+          .fixedSize(horizontal: false, vertical: true)
           .relativeLineSpacing(.em(0.333335))
           .markdownTextStyle {
             FontFamilyVariant(.monospaced)

Sources/MarkdownUI/Theme/Theme+DocC.swift

@@ -113,6 +113,7 @@ extension Theme {
     .codeBlock { configuration in
       ScrollView(.horizontal) {
         configuration.label
+          .fixedSize(horizontal: false, vertical: true)
           .relativeLineSpacing(.em(0.225))
           .markdownTextStyle {
             FontFamilyVariant(.monospaced)