defaults: Fix pgdg default keys
Prior to this commit, the gpg key block was wrong (missing 2 space added back
here). It was noticed from from a puppet run on a new node where the following
failures happened:
The following signatures were invalid: EXPKEYSIG 7FCC7D46ACCC4CF8 PostgreSQL Debian Repository Reading package lists... Done W: GPG error: http://apt.postgresql.org/pub/repos/apt stretch-pgdg InRelease: The following signatures were invalid: EXPKEYSIG 7FCC7D46ACCC4CF8 PostgreSQL Debian Repository