git: Set push.default to current

Push current branch to branch of same name.
This is useful for new branches as I almost always push those with:
```
	git push -u origin "$(git branch --show-current)"
```

.config/git/config

@@ -33,3 +33,5 @@
 	tool = nvimdiff
 [init]
 	defaultBranch = main
+[push]
+	default = current