Prepare for release (unitaryfund#1143)

* update changelog

* update version to stable

Merge branch 'master' of https://github.com/unitaryfund/mitiq

Prepare to release 0.11.1 (unitaryfund#1030)

* Update changelog.

* Clearer changelog.

* Update version and release date in changelog.

Prepare to release 0.11.0 (unitaryfund#1010)

* Changelog part 1.

* Changelog part 2.

* Changelog part 3.

* Version.

* Changelog.

* What even is this?

* Changelog.

* One more commit.

Release v0.10.0

update version to 0.9.3

Merge pull request unitaryfund#770 from unitaryfund/patch-release-0.9.2

Patch release 0.9.2

Merge pull request unitaryfund#747 from unitaryfund/patch-release-0.9.1

Patch release 0.9.1

Merge pull request unitaryfund#727 from unitaryfund/master

PR from master (0.9.0dev) to release branch (merged without squashing)