Merge pull request github#18866 from michaelnebel/csharp/ccr-call-to-object-tostring

C#: Add cs/call-to-object-tostring to the CCR query suite.

Author: michaelnebel

csharp/ql/src/codeql-suites/csharp-ccr.qls

@@ -7,3 +7,4 @@
       - cs/reference-equality-on-valuetypes
       - cs/self-assignment
       - cs/inefficient-containskey
+      - cs/call-to-object-tostring