astropy/ccdproc: 2.1.1

There are several minor fixes in this release: New Features Improve integration of ImageFileCollection with image combination and document that integration [#762] Other Changes and Additions Add memory_profiler as a test requirement [#739] Updated test suite to use absolute, not relative imports [#735] Bug Fixes test_image_collection.py in the test suite no longer produces permanent files on disk and cleans up after itself. [#738] Change Combiner to allow accepting either a list or a generator [#757] ImageFileCollection now correctly returns an empty collection when an existing collection is filtered restrictively enough to remove all files. [#750] Logging now preserves all of the arguments when the keyword argument names are not used. [#756] Thanks to our contributors These folks made code contributions to this release, which wouldn't have happened without them: Larry Bradley (@larrybradley) Timothy P. Ellsworth-Bowers (@tbowers7) Yash Gondhalekar (@Yash-10) Kelvin Lee (@laserkelvin) Pey Lian Lim (@pllim) Jenna Ryon (@jryon) Thanks to these people who have helped by opening multiple issues with ccdproc -- many of the improvements come from these issues: Juan Cabanela (@JuanCab) @mheida Sara Ogaz (@SaOgaz) Jean-Paul Ventura (@jvntra) Kerry Paterson (@KerryPaterson) Jane Rigby (@janerigby) Kris Stern (@kakirastern) Alexa Villaume (@AlexaVillaume) Brian York (@york-stsci) Sylvielsstfr (@sylvielsstfr