Prepare for v2.3.0

[vstehle]

Update the changelog and provision the conformance profile GUID for v2.3.0.

[xypron]

$ git shortlog v2.2.0..HEAD
Vincent Stehlé (15):
      CI: use apt-get to fix warnings
      trivial: move some footnotes closer to their referrer
      chapter2: disambiguate collation protocol
      chapter3: deprecate spin tables
      chapter2: require authenticated fmp capsules for fw update
      trivial: add one typo to our list
      references: bump psci version
      references: bump dt-schema version
      references: bump bbr version
      Update UEFI version to 2.10 A
      CI: specify Sphinx version to fix the build
      CI: specify ubuntu version to fix the build
      references: bump devicetree schema tools, psci and smccc
      trivial: add required global variables anchor
      chapter2: add boot manager requirements

Deprecating spin tables seem to be missing in the changelog.

Otherwise
Reviewed-by: @xypron

[vstehle]

Hi @xypron, thanks for the review (and @ricardosalveti). You made me doubt; but yes, spin table deprecation is there.

[vstehle]

Approved during the EBBR call of Dec 4; we should release EBBR v2.3.0 soon.