GLM v1.6.0

Diff since v1.5.1

Closed issues:

• License terms incomplete? (#441)
• Difference between passing data directly or via formula for glm (#450)
• project.toml version and released versions appear to be out of sync (#463)

Merged pull requests:

• Implement fstatistic (#424) (@OndrejSlamecka)
• Add residuals convenience function to docs (#445) (@ym-han)
• Update license to indicate GPL dependency. (#447) (@rcurtin)
• Add ftest to the manual (#451) (@nalimilan)
• Fix manual deployment (#452) (@nalimilan)
• CompatHelper: bump compat for "SpecialFunctions" to "2.0" (#457) (@github-actions[bot])
• compat fixes for Julia v1.8 (#459) (@dkarrasch)
• Update doctests for pivot (#460) (@palday)
• use StatsModels.isnested instead of defining new issubmodel func (#462) (@kleinschmidt)
• change version back to 1.6.0 since 1.6.0 was never released (#464) (@kleinschmidt)