macos: Bump deployment target from 10.15 to 14.5

As Greg said in zulip#1116:

> 10.15 is from 2019, and even increasing to last year's macOS 14
> would be perfectly fine.

macos/Podfile

@@ -1,6 +1,6 @@
 # This should match the macOS Deployment Target
 # (in Xcode, that's in project > Runner > Info)
-platform :osx, '10.15'
+platform :osx, '14.5'
 
 # CocoaPods analytics sends network stats synchronously affecting flutter build latency.
 ENV['COCOAPODS_DISABLE_STATS'] = 'true'

macos/Podfile.lock

@@ -183,6 +183,6 @@ SPEC CHECKSUMS:
   video_player_avfoundation: 7c6c11d8470e1675df7397027218274b6d2360b3
   wakelock_plus: 4783562c9a43d209c458cb9b30692134af456269
 
-PODFILE CHECKSUM: bcc9d1ecd86955a8f8907c4c114e92d74ab88cc1
+PODFILE CHECKSUM: bd6842df0dd91920553fbfacd50c921f7e63a62f
 
 COCOAPODS: 1.16.2

macos/Runner.xcodeproj/project.pbxproj

@@ -422,7 +422,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.15;
+				MACOSX_DEPLOYMENT_TARGET = 14.5;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = macosx;
 				SWIFT_COMPILATION_MODE = wholemodule;
@@ -501,7 +501,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.15;
+				MACOSX_DEPLOYMENT_TARGET = 14.5;
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = macosx;
@@ -548,7 +548,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.15;
+				MACOSX_DEPLOYMENT_TARGET = 14.5;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = macosx;
 				SWIFT_COMPILATION_MODE = wholemodule;