Make `Constructor` as `protected`.

docs/en/Tutorials/Part-10.md

@@ -626,7 +626,7 @@ public abstract class BookAppService_Tests<TStartupModule> : BookStoreApplicatio
     private readonly IBookAppService _bookAppService;
     private readonly IAuthorAppService _authorAppService;
 
-    public BookAppService_Tests()
+    protected BookAppService_Tests()
     {
         _bookAppService = GetRequiredService<IBookAppService>();
         _authorAppService = GetRequiredService<IAuthorAppService>();

docs/en/Tutorials/Part-4.md

@@ -93,7 +93,7 @@ public abstract class BookAppService_Tests<TStartupModule> : BookStoreApplicatio
 {
     private readonly IBookAppService _bookAppService;
 
-    public BookAppService_Tests()
+    protected BookAppService_Tests()
     {
         _bookAppService = GetRequiredService<IBookAppService>();
     }
@@ -219,7 +219,7 @@ public abstract class BookAppService_Tests<TStartupModule> : BookStoreApplicatio
 {
     private readonly IBookAppService _bookAppService;
 
-    public BookAppService_Tests()
+    protected BookAppService_Tests()
     {
         _bookAppService = GetRequiredService<IBookAppService>();
     }