Update changelog.md

Merge pull request bolt#7914 from bolt/release/3.7.3

Prepare release 3.7.3

Merge pull request bolt#7884 from bolt/release/3.7.2

Prepare release 3.7.2

Merge pull request bolt#7857 from bolt/release/3.7.1

Prepare release 3.7.1

Merge pull request bolt#7826 from bolt/version-bump-to-php-71

Version bump to PHP 7.1

Merge pull request bolt#7825 from bolt/release/3.6.11

Prepare release 3.6.11

Merge pull request bolt#7803 from bolt/release/3.6.10

Preparing release 3.6.10

Merge pull request bolt#7785 from bolt/release/3.6.9

Release/3.6.9

Merge pull request bolt#7777 from bolt/release/3.6.8

Prepare release of Bolt 3.6.8

Prepare release of Bolt 3.6.7 (bolt#7771)

* Make sure `accept_file_types` is an INDEXED array

* Blacklist some common PHP file extensions

* code formatting

* Refactored the thing

* CS fixes

* Fix typo.

* Third time's a charm

* Remove outdated comment

* Add a description in config

* Prepare release of Bolt 3.6.7

* Update config.yml.dist

* Compare filename extension lowercased

* Prepare release of Bolt 3.6.7

* Updating changelog / lock