tests/test-gendoc-ro.t

typing: simplify archive.gz writing and drop a few pytype suppressions

I was waiting until 3.8 to use `Literal` to fix this, but there's also the ":"
and "|" characters that are passed along here, meant only for the non-gz archive
types.  But manipulating what the local caller passes is silly- we know we're
writing, so just open it for writing.  As an added bonus, PyCharm stops flagging
the call too (since it doesn't know about pytype suppression comments).

#require docutils gettext

Error: the current ro localization has some rst defects exposed by
moving pager to core. These two warnings about references are expected
until the localization is corrected.
  $ $TESTDIR/check-gendoc ro
  checking for parse errors
  gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.
  gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.