maintained version of hdf5

[jedbrown]

The hdf5 lib here has become unmaintained and doesn't work with recent 1.14.x releases. We might want to switch to the maintained fork.

[Tehforsch]

Didn't realize there was a new fork, the lack of 1.14 support had been bothering me for a while (I always kept the fixed-hdf5-version branch in this repo pointed at a PR that fixes the issue). I am only worried about the required compiler version - the fork says 1.80 or later is required, which is fairly recent. Then again, this is a nightly-only library anyways, so the amount of people using a pre-1.80 version is probably low. I will change the dependency to the fork for now.