CI: github: add a few more words to the codespell ignore list

This adds "referer,ot,uint,iif,fo,keep-alives" to the ignore list:
  - "referer" is the well-known HTTP header field name (with its
    spelling error)
  - "ot" appears a lot in the opentracing contrib.
  - "iff" often stands for "if and only if"
  - "fo" appears as a test string in tests/ist.c (could possibly be
     changed)
  - "keep-alives" appears as a noon in "...enable TCP keep-alives".
1 file changed