[cpp-qt-client] Fix warnings

[MartinDelille]

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cc @ravinikam @stkrwork @etherealjoy @muttleyxd

[wing328]

can you please update the samples?

 void OauthCredentials::setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret){
@@ -206,7 +206,7 @@ void OauthPassword::link()
 
 void OauthPassword::unlink()
 {
-    disconnect(this,0,0,0);
+    disconnect(this, nullptr, nullptr, nullptr);
 }
 
 void OauthPassword::setVariables(QString tokenUrl, QString scope, QString clientId, QString clientSecret, QString username, QString password){
Perform git status
HEAD detached at pull/14056/merge
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
	modified:   samples/client/petstore/cpp-qt/client/PFXOauth.cpp

no changes added to commit (use "git add" and/or "git commit -a")

ref: https://github.com/OpenAPITools/openapi-generator/actions/runs/3490844364/jobs/5842865742

[MartinDelille]

Sorry! Long time I didn't contribute and I just forgot! I would have check the issue in the CI anyway! 😄

[wing328]

@MartinDelille No problem :) Always appreciate your contributions 👍

Tested locally and the result is good:

QDEBUG : UserApiTests::loginUserTest() "{\"code\":200,\"type\":\"unknown\",\"message\":\"logged in user session:1668931788895\"}"
PASS   : UserApiTests::loginUserTest()
PASS   : UserApiTests::logoutUserTest()
QDEBUG : UserApiTests::updateUserTest() got a request body
PASS   : UserApiTests::updateUserTest()
PASS   : UserApiTests::cleanupTestCase()
Totals: 10 passed, 0 failed, 0 skipped, 0 blacklisted, 121ms
********* Finished testing of UserApiTests *********
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  3.797 s
[INFO] Finished at: 2022-11-20T00:09:49-08:00
[INFO] ------------------------------------------------------------------------