Remove print statements from ruby_runtime.bzl (#84)

This reduces noise in the build by removing messages that look like:
```
DEBUG: [...]/ruby_runtime.bzl:5:10: download and extract ruby-build
DEBUG: [...]ruby_runtime.bzl:13:10: ./bin/ruby-build --verbose 2.7.0 ./build
```

Author: adzenith

ruby/private/toolchains/ruby_runtime.bzl

@@ -2,15 +2,13 @@ load("//ruby/private:constants.bzl", "RULES_RUBY_WORKSPACE_NAME")
 load("//ruby/private/toolchains:repository_context.bzl", "ruby_repository_context")
 
 def _install_ruby_version(ctx, version):
-    print("download and extract ruby-build")
     ctx.download_and_extract(
         url = "https://github.com/rbenv/ruby-build/archive/v20200727.tar.gz",
         sha256 = "71679d49d9190250059eaa0bc0bedd080c00a523ec47662f559f7629f71772ea",
         stripPrefix = "ruby-build-20200727",
     )
 
     install_path = "./build"
-    print("./bin/ruby-build", "--verbose", version, install_path)
     ctx.execute(
         ["./bin/ruby-build", "--verbose", version, install_path],
         quiet = False,