cut a v1.15.3 release

[flavorjones]

contents

• Fix argument typechecking in Text.new, CDATA.new, and Schema.from_document #2920
• fix: do not dup text siblings in reparent_node_with(xmlAddChild) #2918
• Serializing unparented HTML node on JRuby #2895

backported onto v1.15.2 with:

git cherry-pick -x \
    79b8b4fe \
    2c7c68b3 \
    12cb1c12 \
    b581c771 \
    3b1bc8ee \
    240a805f \
    6325ed6d \
    6230318f \
    0fad7263 \
    38b4dcec \
    547c27c0 \
    11bb4d70 \
    54b2f6ab \
    7911c0bf

checklist

• make sure CI is green!
  • https://github.com/sparklemotion/nokogiri/actions/runs/5465001965
• update CHANGELOG.md and lib/nokogiri/version/constant.rb
• create a git tag
• run scripts/build-gems and make sure it completes and all the tests pass
• for g in gems/*.gem ; do gem push $g ; done
• create a release at https://github.com/sparklemotion/nokogiri/releases and provide sha2 checksums
  • https://github.com/sparklemotion/nokogiri/releases/tag/v1.15.3
• update nokogiri.org