v0.23.218

Update gitter and license badge links in README (#25)
Improved 'SPIRV-Headers' build time (#24)
Add 'libjpeg-turbo' package (#20)
Update 'libxml2' to v2.9.7-p0 (#19)
Add 'libs3' Package (#18)
Add 'SPIRV-Tools' package (#23)
Update package-request.md (#15)

HunterGate(
    URL "https://github.com/cpp-pm/hunter/archive/v0.23.218.tar.gz"
    SHA1 "9a3594a61227967fb92159339ba326701b287b19"
)