added appveyor.yml file for the CI build to be able to use the xamarin license

Author: Michael Hallett

RestSharp.sln

@@ -18,6 +18,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".nuget", ".nuget", "{1B3F12
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Meta", "Meta", "{C5B02FAA-6A0A-4BF9-BBD4-82FD2DCBF669}"
 	ProjectSection(SolutionItems) = preProject
+		appveyor.yml = appveyor.yml
 		CONTRIBUTING.markdown = CONTRIBUTING.markdown
 		README.markdown = README.markdown
 		readme.txt = readme.txt

appveyor.yml

@@ -0,0 +1,15 @@
+version: 105.0.1.{build}
+before_build:
+- nuget restore RestSharp.sln
+- appveyor RegisterXamarinLicense -Email %xamarin_email% -Password %xamarin_password% -Product Android
+- appveyor RegisterXamarinLicense -Email %xamarin_email% -Password %xamarin_password% -Product iOS
+build:
+  project: RestSharp.sln
+  verbosity: minimal
+after_build:
+- appveyor UnregisterXamarinLicense -Email %xamarin_email% -Password %xamarin_password%
+environment:
+  xamarin_email:
+    secure: zM9+mVyEGu7yKbL64GG5h0ulFnmt6/jfq8jynL2yCOw=
+  xamarin_password:
+    secure: sRp5YM8LTyje4swi/8p5tQ==