Set up dependabot to automatically keep dependency versions up to date

[guenp]

See comment by @jenshnielsen here: #40 (comment)

We should set up dependabot to keep the requirements that we perform most of the actual ci testing against (in requirements.txt) up to date and automatically open new pull requests when a new package is released. See also the Qcodes repo for how this is set up.

[hxri]

Hi Is this done? If not can I work on it?

[guenp]

Hi @hxri! No not yet, if you're still interested please do! I'll add a Hacktoberfest label as well.

[hxri]

@guenp Sure! I'll start working on it.

[aditirao7]

Hi! @hxri are you still working on this? If not may I take it up?