📝 fixed Clang version (#3040)

README.md

@@ -1111,7 +1111,7 @@ The following compilers are currently used in continuous integration at [Travis]
 | Clang 11.0.0 with GNU-like command-line                           | Windows-10.0.17763 | GitHub Actions |
 | Clang 11.0.0 with MSVC-like command-line                          | Windows-10.0.17763 | GitHub Actions |
 | Clang 11.0.0 (11.0.0-2~ubuntu20.04.1)                             | Ubuntu 20.04.2 LTS | GitHub Actions |
-| Clang 12.0.0 (11.0.0-2~ubuntu20.04.1)                             | Ubuntu 20.04.2 LTS | GitHub Actions |
+| Clang 12.0.0 (12.0.0-3ubuntu1~20.04.3)                            | Ubuntu 20.04.2 LTS | GitHub Actions |
 | Clang 13.0.0 (13.0.0-++20210828094952+9c49fee5e7ac-1exp120210828075752.71 | Ubuntu 20.04.2 LTS | GitHub Actions |
 | Visual Studio 14 2015 MSVC 19.0.24241.7 (Build Engine version 14.0.25420.1) | Windows-6.3.9600 | AppVeyor |
 | Visual Studio 15 2017 MSVC 19.16.27035.0 (Build Engine version 15.9.21+g9802d43bc3 for .NET Framework) | Windows-10.0.14393 | AppVeyor |