[BUG] file.retention_schedule always reports changes

[nicholasmhughes]

Description
The file.retention_schedule state function always reports changes, regardless of outcome.

Setup
Make a test directory to operate against:

mkdir /tmp/src
touch /tmp/src/one

Basic state YAML (copied from state function docs):

/tmp/src:
  file.retention_schedule:
    - retain:
        most_recent: 5
        first_of_hour: 4
        first_of_day: 7
        first_of_week: 6    # NotImplemented yet.
        first_of_month: 6
        first_of_year: all
    - strptime_format: example_name_%Y%m%dT%H%M%S.tar.bz2
    - timezone: None

Running it shows that nothing will be deleted, but a changes dictionary with informational data is returned:

local:
----------
          ID: /tmp/src
    Function: file.retention_schedule
      Result: True
     Comment: 0 backups were removed from /tmp/src.
     Started: 20:07:11.329835
    Duration: 10.78 ms
     Changes:   
              ----------
              deleted:
              ignored:
                  - one
                  - ..
                  - .
              retained:

Summary for local
------------
Succeeded: 1 (changed=1)
Failed:    0
------------
Total states run:     1
Total run time:  10.780 ms

Expected behavior
States should only report changes when changes are made.

Versions Report*

salt --versions-report

(Provided by running salt --versions-report. Please also mention any differences in master/minion versions.)

Salt Version:
          Salt: 3005.1
 
Dependency Versions:
          cffi: Not Installed
      cherrypy: Not Installed
      dateutil: Not Installed
     docker-py: Not Installed
         gitdb: Not Installed
     gitpython: Not Installed
        Jinja2: 3.1.2
       libgit2: Not Installed
      M2Crypto: Not Installed
          Mako: Not Installed
       msgpack: 1.0.4
  msgpack-pure: Not Installed
  mysql-python: Not Installed
     pycparser: Not Installed
      pycrypto: 2.6.1
  pycryptodome: 3.15.0
        pygit2: Not Installed
        Python: 3.7.3 (default, Oct 31 2022, 14:04:00)
  python-gnupg: Not Installed
        PyYAML: 6.0
         PyZMQ: 24.0.1
         smmap: Not Installed
       timelib: Not Installed
       Tornado: 4.5.3
           ZMQ: 4.3.4
 
System Versions:
          dist: debian 10 buster
        locale: UTF-8
       machine: x86_64
       release: 4.19.0-22-amd64
        system: Linux
       version: Debian GNU/Linux 10 buster