update failing links to new urls

[shimwell]

I was just running the nice depletion/generate_endf71_chain.py script and got a 404 url not found error

so I went to the website and it looks like all the links have changed slightly.

I've been through and updated the links in a few places to get them working again

[shimwell]

Marking as draft as I need to go through and check these one more time when I get some fast internet

[AnderGray]

Testing out the changes. So far generate_endf.py, convert_nndc71.py, and generate_endf71_chain.py working as expected, but come across an error with generate_jeff33.py:

Downloading JEFF33-n.tgz...  469316540  [100.00%]
Traceback (most recent call last):
  File "./generate_jeff33.py", line 128, in <module>
    download(urljoin(base, fname), checksum)
  File "/MYDIR/opt/openmc/data/utils.py", line 110, in download
    "openmc-users@googlegroups.com.".format(local_path))
OSError: MD5 checksum for JEFF33-n.tgz does not match. If this is your first time receiving this message, please re-run the script. Otherwise, please contact OpenMC developers by emailing openmc-users@googlegroups.com.

[AnderGray]

generate_endf71_chain_casl.py working, but generate_tendl_chain.py gives error:

Downloading tendl-download/TENDL-n.tgz... 2986500080  [100.00%]
Extracting tendl-download/TENDL-n.tgz...
Traceback (most recent call last):
  File "./generate_tendl_chain.py", line 117, in <module>
    main()
  File "./generate_tendl_chain.py", line 81, in main
    with open('tendl2019_nuclides.json', 'r') as fh:
FileNotFoundError: [Errno 2] No such file or directory: 'tendl2019_nuclides.json'

[shimwell]

Looks like the hashlib.md5 for the JEFF files have changed.

[shimwell]

Both of these errors appear unrelated to the updating of the endf URL. Shall I fix them in a separate PR or is it best to do the fixes here.

[AnderGray]

In my opinion - stick the changes here