Git hub has removed TLS-1.0 from it’s authentication services. https://githubengineering.com/crypto-removal-notice/

Solutions

Windows Clients

Use Version 2.14.3 (or newer) of Git for Windows and newer include an up-to-date Git Credential Manager for Windows: https://gitforwindows.org/

You can also explicitly update your Git Windows Credential Manager to the latest version, 1.14.0, to get TLS-1.2 support: https://github.com/Microsoft/Git-Credential-Manager-for-Windows/releases/tag/v1.14.0

Visual Studio Clients

It is suggested to update your client to VS 2017 or, if you cannot upgrade, there are two machine-wide registry keys you can set that affect all .NET-based applications on the client machine that you can change… https://developercommunity.visualstudio.com/content/problem/201457/unable-to-connect-to-github-due-to-tls-12-only-cha.html

JDK

TLS-1.2 is default in JDK8 and available in JDK7.
https://blogs.oracle.com/java-platform-group/diagnosing-tls,-ssl,-and-https

Red Hat native Git clients

RH 5 does not support TLS-1.2 and GitHubEngineering suggest updating to newer versions of the OS. RH 6.8 and 7.2 will support TLS-1.2. https://www.linuxquestions.org/questions/blog/mensawater-183304/rhel5-wont-support-tlsv1-1-or-higher-36951/