add .gitattributes to build from git archive

[cho-m]

Was trying to build 2.13.0 release from git archive tarball, but it failed as cmake/modules/.git_archival.txt wasn't substituted causing:

fatal: not a git repository (or any of the parent directories): .git
CMake Error at cmake/modules/DynamicVersion.cmake:518 (message):
  Project source is neither a git repository nor a git archive:

Also removing ref-names which can lead to non-reproducible git archive, see:

• pypa/setuptools-scm@9ea57a0

---

On side note, currently unable to recursive clone repository. The wiki revision does not exist. Was this a local wiki change missing from remote?

[evaleev]

@cho-m re: wiki, yes indeed missed pushes (and updates), should be ok as of 72792c1. Thanks for the heads-up!