Gammapy v0.18.2 release

[axeld...@googlemail.com]

Dear Gammapy folks,

We are happy  to announce the release of Gammapy v0.18.2. Thanks to all who contributed!

Gammapy v0.18.2 comes with a more uniform API and many new features, such as computing 

flux maps and light curves in energy bands. A complete summary of all recent changes can be found here:

https://docs.gammapy.org/0.18.2/changelog.html#nov-4th-2020

Instructions how to install / update Gammapy using `conda` can be found here:

https://docs.gammapy.org/0.18.2/install/index.html#installation

Please get in contact if you have feedback for us, find issues or if you have questions of any kind:

https://gammapy.org/contact.html

Kind regards, 

Axel, for the Gammapy developer team