datetime: fix values of unspecified fields in dt.parse() datetime object can be created using `datetime.new()` and `datetime.parse()`. `datetime.new()` sets values of unspecified fields to appropriate values of fields in a Unix time (00:00:00 UTC on 1 January 1971, Thursday), see commit 43e10ed34949 ("build, lua: built-in module datetime"): ``` tarantool> datetime.new() --- - 1970-01-01T00:00:00Z ... tarantool> datetime.new():totable() --- - sec: 0 min: 0 yday: 1 day: 1 nsec: 0 isdst: false wday: 5 tzoffset: 0 month: 1 year: 1970 hour: 0 ``` The function `datetime.parse` converts an input string with the date and time information into a datetime object. When fields are not specified in a input string their values becomes undefined: ``` tarantool> dt.parse('01:01:01', {format ='%H:%M:%S'}):totable() --- - sec: -59 min: -58 yday: 366 day: 31 nsec: 0 isdst: false wday: 1 tzoffset: 0 month: 12 year: 0 hour: -22 ... tarantool> ``` The commit fixes aforementioned behaviour of `datetime.parse()` by setting values for fields not specified by user to values of appropriate fields of Unix time. NO_DOC=bugfix Fixes #8588 (cherry picked from commit 9ac56a1222e916951010091fbdbfc497f4a4971d)

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.

Generate changelog for 3.1.1 Also, remove unreleased/ entries. NO_DOC=changelog NO_TEST=changelog NO_CHANGELOG=changelog