Prohibit GIT after setting readonly

	---
	 .appveyor.yml | 1 +
	 1 file changed, 1 insertion(+)

	Clarify the actual Visual Studio version [ci skip]

	---
	 .appveyor.yml | 3 ++-
	 1 file changed, 2 insertions(+), 1 deletion(-)

	Silent test-all on AppVeyor

	---
	 .appveyor.yml | 2 +-
	 1 file changed, 1 insertion(+), 1 deletion(-)

	Revert vcpkg.exe to previous release [ci skip]

	The latest fails to extract downloaded zip files.
	---
	 .appveyor.yml | 1 +
	 1 file changed, 1 insertion(+)

to possibly deal with failures like https://ci.appveyor.com/project/ruby/ruby/builds/45097615.

I'm not sure how vcpkg retries things, but at least aria2c seems to attempt downloads 5 times by default.
https://aria2.github.io/manual/en/html/aria2c.html

Looking at the CI log, vcpkg might be already trying it 5 times, but let me give it a try too.

https://github.com/ruby/ruby/commit/0d7292ec734d49def118959d6a80588e7c0f7a39

Although zlib package in vcpkg is still 1.2.12, it should be no
problem in ruby tests.

They removed https://zlib.net/zlib1212.zip because
https://zlib.net/zlib1213.zip was released :thinking_face:

Fix CI failures like:
https://ci.appveyor.com/project/ruby/ruby/builds/45064876/job/bb9biogolh0u2595