The JWT spec apparently specifies that base64 strings in jwts aren't to
be padded - but the common lisp base64 library doesn't know how to
decode unpadded base64 (it signals a condition in that case). This adds
the extra padding characters (a number of `=` characters such that the
length of the string is a multiple of 4) using some FORMAT wizardry (?).
Change-Id: Ic6b66f05db2699bf1f93f870f5dd614c37eccc2d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5781
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: grfn <grfn@gws.fyi>