fix: Fixed some compiler warnings (#5028)

* fix(C4101): unreferenced local variable

* fix(C4189): variable initialized but not referenced

* fix(C4305): narrowing from double to float

* fix(C4457): declaration hiding function parameter

* fix(C4456): shadowing declaration

* fix(C4996): remove deprecations

* chore: add changelog entry

* fix: Remove more unused variables

* fix: removed unused lambda captures

* Update changelog entry

---------

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/singletons/WindowManager.cpp

@@ -750,7 +750,7 @@ void WindowManager::applyWindowLayout(const WindowLayout &layout)
             // out of bounds windows
             auto screens = qApp->screens();
             bool outOfBounds =
-                !getenv("I3SOCK") &&
+                !qEnvironmentVariableIsSet("I3SOCK") &&
                 std::none_of(screens.begin(), screens.end(),
                              [&](QScreen *screen) {
                                  return screen->availableGeometry().intersects(