[Data] Normalize all dates in releases.yml to Date instead of String

[epistrephein]

In _data/releases.yml, 18 of the total 197 dates under the date: key are represented with quotes instead of without.

This has the side effect that when the file is YAML-parsed, these dates are parsed as Strings instead of Dates, creating an unwanted inconsistency of classes.

yaml = YAML.unsafe_load_file('_data/releases.yml')

yaml.find { |y| y['version'] == '3.2.0' }['date']
# => #<Date: 2022-12-25 ((2459939j,0s,0n),+0s,-Infj)>

yaml.find { |y| y['version'] == '3.2.2' }['date']
# => "2023-03-30"

This PR normalizes the 18 dates removing the quotes so that they're all parsed as Date class.

yaml = YAML.unsafe_load_file('_data/releases.yml')

# master
yaml.reject { |item| item['date'].is_a?(Date) }.count
# => 18

# this branch
yaml.reject { |item| item['date'].is_a?(Date) }.count
# => 0

[epistrephein]

Looks like v3.2.3 was also pushed with the release date as String instead of Date (ae9c2b0), I've pushed a fix for it as well.

Any chance to get this merged? @nurse @nagachika