📦 Enable support for git archive installs (#1095)

This patch enables the end-users to succeed installing from GitHub
source Git archive URLs, letting `setuptools-scm` calculate the
distribution version correctly, including the exports of non-tagged
commits[1].

[1] https://github.com/pypa/setuptools_scm#git-archives

Author: webknjaz

.git_archival.txt

@@ -0,0 +1,4 @@
+node: $Format:%H$
+node-date: $Format:%cI$
+describe-name: $Format:%(describe:tags=true,match=*[0-9]*)$
+ref-names: $Format:%D$

.gitattributes

@@ -0,0 +1,5 @@
+# Force LF line endings for text files
+* text=auto eol=lf
+
+# Needed for setuptools-scm-git-archive
+.git_archival.txt  export-subst