C#: Update EntityFramework test

Author: hvitved

csharp/ql/test/library-tests/frameworks/EntityFramework/Dataflow.expected

@@ -3,5 +3,6 @@
 | EntityFrameworkCore.cs:50:18:50:28 | access to local variable taintSource | EntityFrameworkCore.cs:47:31:47:39 | "tainted" |
 | EntityFrameworkCore.cs:51:18:51:46 | (...) ... | EntityFrameworkCore.cs:47:31:47:39 | "tainted" |
 | EntityFrameworkCore.cs:52:18:52:42 | (...) ... | EntityFrameworkCore.cs:47:31:47:39 | "tainted" |
+| EntityFrameworkCore.cs:53:18:53:66 | (...) ... | EntityFrameworkCore.cs:47:31:47:39 | "tainted" |
 | EntityFrameworkCore.cs:60:18:60:24 | access to property Name | EntityFrameworkCore.cs:47:31:47:39 | "tainted" |
 | EntityFrameworkCore.cs:61:18:61:34 | access to property Name | EntityFrameworkCore.cs:47:31:47:39 | "tainted" |

csharp/ql/test/library-tests/frameworks/EntityFramework/EntityFrameworkCore.cs

@@ -50,7 +50,7 @@ void TestDataFlow()
             Sink(taintSource);  // Tainted
             Sink(new RawSqlString(taintSource));  // Tainted
             Sink((RawSqlString)taintSource);  // Tainted
-            Sink((RawSqlString)(FormattableString)$"{taintSource}");  // Not tainted
+            Sink((RawSqlString)(FormattableString)$"{taintSource}");  // Tainted
 
             // Tainted via database, even though technically there were no reads or writes to the database in this particular case.
             var p1 = new Person { Name = taintSource };