Fix license in package.json

[jvasile]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

docs update

• What is the current behavior? (You can also link to an open issue here)

The package.json shows a license of "MIT" but the LICENSE file shows AGPLv3.

• What is the new behavior (if this is a feature change)?

My recollection is that the license was meant to be AGPLv3, so MIT is a typo. This commit replaces "MIT" in package.json with the SPDX identifier for AGPLv3. Now the two license specifications match.

• Other information:

This bug was committed when Andrew created the repo four years ago. Both the package.json and the LICENSE were part of the very first commit. Does that mean I win the prize for fixing the oldest bug in the codebase?

[cecilia-donnelly]

Thanks @jvasile! :laughing: