Bump actions/checkout from 2 to 2.3.4#29

dependabot[bot] wants to merge 1 commit intomasterrjmholt/csharp-language-server-protocol:masterfrom

dependabot/github_actions/actions/checkout-2.3.4rjmholt/csharp-language-server-protocol:dependabot/github_actions/actions/checkout-2.3.4Copy head branch name to clipboard