Unsupported Jest version warn outputted on every test execution.

[edbzn]

🐛 Bug Report

Actually a warning concerning unsupported jest version is outputted in the console for every test case which pollute the console even if tests are green.

To Reproduce

Steps to reproduce the behavior:

Update ts-jest to 26.1.0 with jest 25.5.4

Expected behavior

Just log the warning once at test suite initialization and not on every test execution.

[ahnpnl]

This we cannot do, the only way is using the version which is compatible.

[ahnpnl]

You can disable this warning message via environment variable introduced in #1821