fix: bump minimum macOS version for SampleApp

```
MacOS/Info.plist : error : The LSMinimumSystemVersion value in the Info.plist (10.11) does not match the SupportedOSPlatformVersion value (10.14) in the project file (if there is no SupportedOSPlatformVersion value in the project file, then a default value has been assumed). Either change the value in the Info.plist to match the SupportedOSPlatformVersion value, or remove the value in the Info.plist (and add a SupportedOSPlatformVersion value to the project file if it doesn't already exist). [/xxx/uno/src/SamplesApp/SamplesApp.netcoremobile/SamplesApp.netcoremobile.csproj::TargetFramework=net7.0-macos]
```

src/SamplesApp/SamplesApp.netcoremobile/MacOS/Info.plist

@@ -13,7 +13,7 @@
 	<key>CFBundleVersion</key>
 	<string>1</string>
 	<key>LSMinimumSystemVersion</key>
-	<string>10.11</string>
+	<string>10.14</string>
 	<key>CFBundleDevelopmentRegion</key>
 	<string>en</string>
 	<key>CFBundleInfoDictionaryVersion</key>