Update install_requires to support Django 2.2

[cwdavies]

Fix ERROR: ccdb5-ui 1.6.1 has requirement Django<1.12,>=1.11, but you'll have django 2.0.13 which is incompatible.

Changes

• Django>=1.11,<1.12 -> Django>=1.11,<2.3 in setup.py

Testing

• tox

py36-dj111 create: /Users/DaviesC/Projects/CFPB/ccdb5-ui/.tox/py36-dj111
py36-dj111 installdeps: coverage==4.5.1, Django>=1.11,<1.12
py36-dj111 installed: -e git+https://github.com/cfpb/ccdb5-ui.git@fe6c6c39f99cacb4f88acfdc99a7ab7e7942d217#egg=ccdb5_ui,coverage==4.5.1,Django==1.11.29,pytz==2019.3
py36-dj111 run-test-pre: PYTHONHASHSEED='1763659960'
py36-dj111 run-test: commands[0] | coverage erase
py36-dj111 run-test: commands[1] | coverage run ./manage.py test
System check identified no issues (0 silenced).
...
----------------------------------------------------------------------
Ran 3 tests in 0.025s

OK
py36-dj111 run-test: commands[2] | coverage report --skip-covered
Name                Stmts   Miss  Cover
---------------------------------------
ccdb5_ui/views.py      22      1    95%
---------------------------------------
TOTAL                  65      1    98%

6 files skipped due to complete coverage.
py36-dj22 create: /Users/DaviesC/Projects/CFPB/ccdb5-ui/.tox/py36-dj22
py36-dj22 installdeps: coverage==4.5.1, Django>=2.2,<2.3
py36-dj22 installed: -e git+https://github.com/cfpb/ccdb5-ui.git@fe6c6c39f99cacb4f88acfdc99a7ab7e7942d217#egg=ccdb5_ui,coverage==4.5.1,Django==2.2.11,pytz==2019.3,sqlparse==0.3.1
py36-dj22 run-test-pre: PYTHONHASHSEED='1763659960'
py36-dj22 run-test: commands[0] | coverage erase
py36-dj22 run-test: commands[1] | coverage run ./manage.py test
System check identified no issues (0 silenced).
...
----------------------------------------------------------------------
Ran 3 tests in 0.037s

OK
py36-dj22 run-test: commands[2] | coverage report --skip-covered
Name                      Stmts   Miss  Cover
---------------------------------------------
ccdb5_ui/config/urls.py       6      2    67%
ccdb5_ui/views.py            22      1    95%
---------------------------------------------
TOTAL                        65      3    95%

5 files skipped due to complete coverage.
___________________________________ summary ____________________________________
  py36-dj111: commands succeeded
  py36-dj22: commands succeeded
  congratulations :)

Checklist

• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Passes all existing automated tests

[coveralls]

Coverage remained the same at 99.872% when pulling 1611c5b on fix-django-error into fe6c6c3 on master.