add pre-authentication to bashrc function gp()

there is a program in randomuser/utils which acts as an
authentication manager for tildegit. it doesn't work right.
when the tildegit password has not been requested recently,
instead of popping up a prompt, it will just return an auth
error. i honestly don't know why this is happening, but doing
this makes gpg-agent aware of the decryption and allows the
password to be accessed by git without user intervention.

bash/bashrc

@@ -50,6 +50,8 @@ git_main_branch () {
 }
 
 gp() {
+	# a bodge -- git authentication doesn't work quite right
+	pash c tildegit
 	git push -u origin $(git_main_branch)
 }