chore(deps): update flask-caching requirement from ~=1.4 to ~=1.8

[dependabot-preview]

Updates the requirements on flask-caching to permit the latest version.

Release notes

Sourced from flask-caching's releases.

1.8.0

Released on November 24th 2019

Breaking: Dropped support for Python 2

• Add option to specify if None is a cached value or not. See PR #140 and #141.
• Allow to use __caching_id__ rather than __repr__ as an object caching key. PR #123.
• The RedisCache backend now support generating the key_prefix via a callable. PR #109.
• Emit a warning if the CACHE_TYPE is set to filesystem but no CACHE_DIR is set.
• Fixes Google App Engine Memcache backend. See issue #120 for more details.
• Various documentation updates and fixes.

Changelog

Sourced from flask-caching's changelog.

Version 1.8.0

Released 2019-11-24

• BREAKING: Removed support for Python 2. Python 3.5 and upwards are
  supported as of now.
• Add option to specify if None is a cached value or not. See
  PR [#140](https://github-redirect.dependabot.com/sh4nks/flask-caching/issues/140) <https://github-redirect.dependabot.com/sh4nks/flask-caching/pull/140>_ and
  [#141](https://github-redirect.dependabot.com/sh4nks/flask-caching/issues/141) <https://github-redirect.dependabot.com/sh4nks/flask-caching/pull/141>_.
• Allow to use __caching_id__ rather than __repr__ as an object
  caching key.
  PR [#123](https://github-redirect.dependabot.com/sh4nks/flask-caching/issues/123) <https://github-redirect.dependabot.com/sh4nks/flask-caching/pull/123>_.
• The RedisCache backend now support generating the key_prefix via a callable.
  PR [#109](https://github-redirect.dependabot.com/sh4nks/flask-caching/issues/109) <https://github-redirect.dependabot.com/sh4nks/flask-caching/pull/109>_.
• Emit a warning if the CACHE_TYPE is set to filesystem but no
  CACHE_DIR is set.
• Fixes Google App Engine Memcache backend.
  See issue [#120](https://github-redirect.dependabot.com/sh4nks/flask-caching/issues/120) <https://github-redirect.dependabot.com/sh4nks/flask-caching/issues/120>_ for
  more details.
• Various documentation updates and fixes.

Version 1.7.2

Released 2019-05-28

This is the last version supporting Python 2!

• Do not run a cached/memoized function if the cached return value is None.
  PR [#108](https://github-redirect.dependabot.com/sh4nks/flask-caching/issues/108) <https://github-redirect.dependabot.com/sh4nks/flask-caching/pull/108>_.

Version 1.7.1

Released 2019-04-16

• Fix introspecting Python 3 functions by using varkw.
  PR [#101](https://github-redirect.dependabot.com/sh4nks/flask-caching/issues/101) <https://github-redirect.dependabot.com/sh4nks/flask-caching/pull/101>_.
• Remove leftover files (uwsgi.py) in PyPI package. See issue
  [#102](https://github-redirect.dependabot.com/sh4nks/flask-caching/issues/102) <https://github-redirect.dependabot.com/sh4nks/flask-caching/issues/102>_ for more details.

Version 1.7.0

Released 2019-03-29

... (truncated)

Commits

• b8e2fa6 Flask-Caching 1.7.2 -> 1.8.0
• cb20a78 Add Python 3.8 support
• 7d5bee7 Restructure changelog
• af68ad2 Update CHANGELOG for 1.8
• 22e5af4 Unpin pytest dependency as we do not depend on Python 2 anymore
• 11c5afe Fix Google App Engine backend
• 258bd0a Implement response_filter for memoized functions
• 092e7cb Fix docs and add a template fragment caching example
• 2f5d4bd Update docs to reflect the current functionality. Fixes #130
• dd5cdc2 remove duplicate unlink function definition
• Additional commits viewable in compare view

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[codecov]

Codecov Report

Merging #6617 into development will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff              @@
##           development    #6617   +/-   ##
============================================
  Coverage        65.06%   65.06%           
============================================
  Files              297      297           
  Lines            15258    15258           
============================================
  Hits              9927     9927           
  Misses            5331     5331

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