NatLibFi/Skosmos: Skosmos 2.11

This is a minor version release (2.11) of Skosmos that brings a few small improvements and bug fixes.

• #913/#1174 Count deprecated concepts separately in vocabulary metadata
• #1100/#1176 Define order for more vocabulary home page properties
• #1166 Specify SPARQL endpoint URL via environment variable
• #1159 Add topbar-container CSS hook (credit: @danmichaelo)

• #1156/#1157/#1162 Docker fails to install Composer dependencies (credit: @jrvosse)

• #1147/#1168 Switch to GitHub Actions CI instead of Travis CI
• Migrate to new Scrutinizer PHP analysis engine

See the upgrade instructions in the wiki for information about upgrading from earlier versions.