git: Set receive.fsckObjects for additional protection against in-flight object corruption

See
https://people.kernel.org/monsieuricon/cross-fork-object-sharing-in-git-is-not-a-bug

git/.gitconfig

@@ -63,6 +63,8 @@
 	autosquash = true
 	autoStash = true
 	updateRefs = true
+[receive]
+	fsckObjects = true
 [sendemail]
 	smtpserver = /usr/bin/msmtp
 [user]