[Data] Normalize all dates to Date instead of String

[epistrephein]

In _data/releases.yml, 3 of the total 229 dates under the date: key are written with quotes instead of without quotes.

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.

This PR normalizes the 3 dates removing the quotes so that they're all parsed as Date class.

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

# master
yaml.filter_map { |i| i['version'] unless i['date'].is_a?(Date) }
# => ["3.3.10", "3.3.9", "3.2.9"]
yaml.find { |i| i['version'] == '3.3.9' }['date']
# => "2025-07-24"


# this branch
yaml.filter_map { |i| i['version'] unless i['date'].is_a?(Date) }
# => []
yaml.find { |i| i['version'] == '3.3.9' }['date']
# => #<Date: 2025-07-24 ((2460881j,0s,0n),+0s,-Infj)>

(see #3566, #3375 and #3146 for the same fix some time ago)