Add php 8.1 to testing of apps

[nickvergessen]

• Update master php testing versions activity#776
• Update master php testing versions files_pdfviewer#586
• Update master php testing versions firstrunwizard#687
• Update master php testing versions logreader#690
• Update master php testing versions nextcloud_announcements#99
• Update master php testing versions notifications#1179
• Update master php testing versions password_policy#340
• Update master php testing versions photos#1072
• Update master php testing versions privacy#755
• Update master php testing versions recommendations#509
• Update master php testing versions viewer#1200
• Update master php testing versions announcementcenter#455
• Update master php testing versions backup#249
• Update master php testing versions circles#994
• Update master php testing versions data_request#64
• Update master php testing versions deck#3688
• Update master php testing versions end_to_end_encryption#288
• Update master php testing versions files_accesscontrol#235
• Update master php testing versions files_automatedtagging#553
• Update master php testing versions files_retention#156
• Update master php testing versions flow_notifications#48
• Update master php testing versions groupfolders#1944
• Update master php testing versions impersonate#152
• Update master php testing versions quota_warning#97
• Update master php testing versions sharepoint#122
• Update master php testing versions spreed#7090
• Update master php testing versions terms_of_service#711
• Update master php testing versions workflow_pdf_converter#387
• Update master php testing versions workflow_script#114
• Update master php testing versions bruteforcesettings#356
• Update master php testing versions files_antivirus#225
• Update master php testing versions files_downloadactivity#88
• Update master php testing versions files_downloadlimit#73
• Update master php testing versions files_zip#67
• Update master php testing versions forms#1157
• Update master php testing versions globalsiteselector#64
• Update master php testing versions guests#875
• Update master php testing versions officeonline#288
• Update master php testing versions registration#413
• Update master php testing versions richdocuments#2122
• Update master php testing versions suspicious_login#628
• Update master php testing versions twofactor_totp#1196
• Update master php testing versions twofactor_u2f#1001
• Update master php testing versions user_oidc#411
• Update master php testing versions user_saml#592

[nickvergessen]

Warning: setup-php v1 is deprecated.
Please upgrade to v2 - https://setup-php.com/w/Switch-to-v2
Error: setup-php v1 supports only PHP 5.6 to 8.0.
Please upgrade to v2 - https://setup-php.com/w/Switch-to-v2

If the tests fail with this, please apply the following change:
nextcloud/recommendations@691b159