chore: Make overridden synchronized Throwable methods synchronized

Author: Christopher-Chianelli

jpyinterpreter/src/main/java/ai/timefold/jpyinterpreter/types/errors/GeneratorExit.java

@@ -45,7 +45,7 @@ public GeneratorExit(PythonLikeType type, List<PythonLikeObject> args) {
      * @return this
      */
     @Override
-    public Throwable fillInStackTrace() {
+    public synchronized Throwable fillInStackTrace() {
         // Do nothing
         return this;
     }

jpyinterpreter/src/main/java/ai/timefold/jpyinterpreter/types/errors/PythonBaseException.java

@@ -65,7 +65,7 @@ public PythonBaseException(PythonLikeType type, String message) {
     }
 
     @Override
-    public Throwable initCause(Throwable cause) {
+    public synchronized Throwable initCause(Throwable cause) {
         super.initCause(cause);
         if (cause instanceof PythonLikeObject pythonError) {
             $setAttribute("__cause__", pythonError);

jpyinterpreter/src/main/java/ai/timefold/jpyinterpreter/types/errors/StopAsyncIteration.java

@@ -48,7 +48,7 @@ public PythonLikeObject getValue() {
      * @return this
      */
     @Override
-    public Throwable fillInStackTrace() {
+    public synchronized Throwable fillInStackTrace() {
         // Do nothing
         return this;
     }

jpyinterpreter/src/main/java/ai/timefold/jpyinterpreter/types/errors/StopIteration.java

@@ -49,7 +49,7 @@ public PythonLikeObject getValue() {
      * @return this
      */
     @Override
-    public Throwable fillInStackTrace() {
+    public synchronized Throwable fillInStackTrace() {
         // Do nothing
         return this;
     }