datetime: remove unused function datetime_gmtoff The function `datetime_gmtoff()` has been introduced in commit aec6fbac1f22 ("datetime: implement date.isdst") for a function `datetime_increment_by()`. In commit 6ca072853034 ("datetime: fix interval arithmetic for DST") the function `datetime_increment_by()` has been updated and call of the function `datetime_gmtoff()` was removed. `datetime_gmtoff` is dead code now. The patch removes `datetime_gmtoff()`. NO_CHANGELOG=codehealth NO_DOC=codehealth NO_TEST=codehealth (cherry picked from commit 625afe418151de1015483ed24acaa57e1f85efb3)

datetime: fix typos The patch fixes a number of typos in datetime source code. NO_CHANGELOG=codehealth NO_DOC=codehealth NO_TEST=codehealth (cherry picked from commit c9c5b9f139ccbf5372d1568827fbb50bec7239bb)

lua-yaml: wrap large doubles in quotes Since tarantool/luajit@a16313f large exponent double strings are not considered convertible to number. It broke encoding lua objects to YAML because single quotes weren't considered necessary for decoding. This commit adds wrapping of every string containing infinite double values into a single quotes. Closes #10164 NO_DOC=bug fix (cherry picked from commit 7c3f42590240525d2e543305b6c289ddb30054a2)

schema: add missing downgrade versions

Dummy commit.