Add .gitattributes (#5)

Author: defunctl

.gitattributes

@@ -0,0 +1,12 @@
+# Path-based git attributes
+# https://www.kernel.org/pub/software/scm/git/docs/gitattributes.html
+
+# Ignore paths when git creates an archive of this package
+/.git*                  export-ignore
+/.editorconfig          export-ignore
+/.env.testing           export-ignore
+/.env.testing.slic      export-ignore
+/codeception.dist.yml   export-ignore
+/codeception.slic.yml   export-ignore
+/phpstan.neon.dist      export-ignore
+/tests                  export-ignore