Bump maven-site-plugin from 3.8.2 to 3.9.1#9

dependabot[bot] wants to merge 1 commit intomasterregisd/jflex:masterfrom

dependabot/maven/org.apache.maven.plugins-maven-site-plugin-3.9.1regisd/jflex:dependabot/maven/org.apache.maven.plugins-maven-site-plugin-3.9.1Copy head branch name to clipboard