pubmed: ignore empty map during baseline update

See merge request webgroup/fatcat!145

> NLM produces a baseline set of PubMed citation records in XML format
for download on an annual basis. The annual baseline is released in
December of each year. --
https://ftp.ncbi.nlm.nih.gov/pubmed/updatefiles/README.txt

Last occurence Dec 8, 2022. Since we do not know the exact date, but the
Pubmed docs explicitly state "December", we ignore empty map error in
this month.

These could be replaced by subsets of data (eg, using jq) in the future.

small fixes to editing process (python and rust)

See merge request webgroup/fatcat!139

rust: refactor closer to 'macaroon' crate

See merge request webgroup/fatcat!143

Much fo the changes here are to deal with the 'ByteString' type that is
included as part of the macaroons library itself.

rust: fill changelog gap helper tool

See merge request webgroup/fatcat!142

"A man is not dead while his name is still spoken."

dblp import iteration

See merge request webgroup/fatcat!141