fix: require iOS 15 for app targets (#4890)

Co-authored-by: root <root@hermes.proxmox>

Author: cagnulein

build-qdomyos-zwift-Qt_5_15_2_for_iOS-Debug/qdomyoszwift.xcodeproj/project.pbxproj

@@ -4730,6 +4730,7 @@
 					../../Qt/5.15.2/ios/include/QtCore/5.15.2/QtCore/,
 					../../Qt/5.15.2/ios/include/QtSql,
 				);
+				IPHONEOS_DEPLOYMENT_TARGET = 15.0;
 				LIBRARY_SEARCH_PATHS = (
 					/Users/cagnulein/Qt/5.15.2/ios/plugins/platforms,
 					/System/Library/Frameworks/,
@@ -4933,6 +4934,7 @@
 					../../Qt/5.15.2/ios/include/QtCore/5.15.2/QtCore/,
 					../../Qt/5.15.2/ios/include/QtSql,
 				);
+				IPHONEOS_DEPLOYMENT_TARGET = 15.0;
 				LIBRARY_SEARCH_PATHS = (
 					/Users/cagnulein/Qt/5.15.2/ios/plugins/platforms,
 					/System/Library/Frameworks/,