Enable lean releases

[skip ci]

.gitattributes

@@ -0,0 +1,13 @@
+/.coveralls.yml       export-ignore
+/.gitattributes       export-ignore
+/.gitignore           export-ignore
+/.phan                export-ignore
+/.php_cs.dist         export-ignore
+/.phpstan.neon        export-ignore
+/.stickler.yml        export-ignore
+/.travis.yml          export-ignore
+/Makefile             export-ignore
+/infection.json.dist  export-ignore
+/phpunit.xml.dist     export-ignore
+/psalm.xml            export-ignore
+/tests                export-ignore