COMP: Fix -Wdeprecated-declarations related to QProcess::pid()

This commit fixes warnings like the following:

  /path/to/CTK/Libs/CommandLineModules/Backend/LocalProcess/ctkCmdLineModuleProcessWatcher.cpp:104:26: warning: ‘Q_PID QProcess::pid() const’ is deprecated: Use processId() instead [-Wdeprecated-declarations]
    104 |   if (::kill(process.pid(), SIGSTOP))
        |                          ^

Libs/CommandLineModules/Backend/LocalProcess/ctkCmdLineModuleProcessWatcher.cpp

@@ -101,7 +101,11 @@ void ctkCmdLineModuleProcessWatcher::pauseProcess()
   if (processPaused || !futureInterface.isPaused()) return;
 
 #ifdef Q_OS_UNIX
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 15, 0))
+  if (::kill(process.processId(), SIGSTOP))
+#else
   if (::kill(process.pid(), SIGSTOP))
+#endif
   {
     // error
     futureInterface.setPaused(false);
@@ -119,7 +123,11 @@ void ctkCmdLineModuleProcessWatcher::resumeProcess()
   if (!processPaused) return;
 
 #ifdef Q_OS_UNIX
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 15, 0))
+  if(::kill(process.processId(), SIGCONT))
+#else
   if(::kill(process.pid(), SIGCONT))
+#endif
   {
     // error
     futureInterface.setPaused(true);