Update .gitattributes

Add phpbench.json
Rearranged the list to be in the same format as on GitHub
Added / in front of the files to have it the same as in the other repositories in the org.

Author: KasperFranz

.gitattributes

@@ -1,15 +1,16 @@
-.gitattributes export-ignore
-.gitignore export-ignore
-.scrutinizer.yml export-ignore
-.travis.yml export-ignore
-composer-require-config.json export-ignore
-Makefile export-ignore
-phive.xml export-ignore
-phpcs.xml.dist export-ignore
-phpstan.neon export-ignore
-psalm.xml export-ignore
 /.github/ export-ignore
 /examples/ export-ignore
+/tests/ export-ignore
+/.gitattributes export-ignore
+/.gitignore export-ignore
+/.scrutinizer.yml export-ignore
+/Makefile export-ignore
+/composer-require-config.json export-ignore
+/composer.lock
+/phive.xml export-ignore
+/phpbench.json export-ignore
+/phpcs.xml.dist export-ignore
 /phpmd.xml.dist export-ignore
+/phpstan.neon export-ignore
 /phpunit.xml.dist export-ignore
-/tests/ export-ignore
+/psalm.xml export-ignore