Log Message:
Update to wordpress 5.5.1.

Changes:

5.5:
- lazy-loaded images
- new sitemap
- autoupdate of plugins and themes
- block editor:
  - block patterns
  - block directory
  - inline image editing

5.5.1:
WordPress Core changes on Trac:

#50882 - Administration: WP 5.5: Cannot attribute content when deleting users
#50998 - Quick/Bulk Edit: Editing posts using bottom "Bulk actions" \ 
dropdown menu doesn't work
#38009 - Comments: #reply-title.comment-reply-title not updating when replying \ 
to an individual
#50845 - Editor: Block patterns: Fix translatable strings (take 2)
#50858 - Site Health: Check PHP notices with site_status_tests filter
#50887 - Site Health: Add site environment to debug information
#50892 - Editor: Some block patterns have text contrast issues with dark themes
#50910 - Sitemaps: 5.5 Sitemap URLs are incorrectly paginated
#50912 - Site Health: flags define WP_AUTO_UPDATE_CORE value as an error
#50919 - Script Loader: Change the jquery handle back to an alias for jquery-core
#50933 - Media: Lazy loading in 5.5 causes flashing of custom logo in Firefox
#50945 - Site Health: don't give a warning when upload_max_size is lower than \ 
max_post_size
#50988 - Upgrade/Install: Pass details about the specific plugin and theme \ 
updates attempted to filters
#50992 - Bootstrap/Load: Remove the ability to alter the list of environment \ 
types in wp_get_environment_type()
#50999 - Script Loader: Disable concatenation for scripts with translations to \ 
ensure they are printed in the right order
#51011 - Upgrade/Install: Empty string comparison on home option during DB \ 
upgrades is invalid
#51018 - Editor: PHP Notice thrown when searching for certain terms via the \ 
Gutenberg block directory
#51151 - Editor: Packages update
#51021 - REST API: Permit uniqueItems keyword in endpoint args
#51146 - REST API: Fix multi-type schemas with integer fields
#51029 - Filesystem API: Typo in variable name causes warning from fclose()
#51042 - Post: missing excerpt
#51050 - Docs: Add docblock for get_the_archive_title() filter
#51052 - Administration: Undefined index: update-supported
#51060 - Docs: Update register_rest_route docblock to reflect additions since 5.5
#51064 - Bootstrap/Load: Consider adding "local" as environment on \ 
WP_ENVIRONMENT_TYPE
#51073 - Administration: Extra padding below the admin bar
#51075 - Docs: Update docs for custom logo functions
#51122 - Docs: add a mention about the use of loading attribute in \ 
wp_get_attachment_image function
#51127 - UI/CSS: Remove non-color related styling from Modern color scheme
#51129 - Upgrade/Install: Only display the auto-update links on the Network \ 
Admin > Themes screen for themes that support the feature
#51337 - Template: wp_terms_checklist not checking selected taxonomy items with \ 
selected_cats option
#51184 - get_the_date() checks $format only for empty variable and fails on \ 
false boolean
#51182 - Theme_Installer_skin::do_overwrite does not work on a Windows server
#38009 - #reply-title.comment-reply-title not updating when replying to an individual
#51123 - commonL10n and other JS globals removed without backwards compatibility
#50848 - Clarify the usage of null for auto_update_{$type} filter
#51081 - Fatal Error - Undefined get_page_templates() in Customizer
#51154 - sitemaps should be initialized before each test is run
#51028 - Dot should be out of the quotes

Block editor changes from GitHub:

PR24609 -  Fix missing selected block highlighting in list view
PR24599 -  Fix specificity for buttons with outline style and background colors
PR24533 -  Fix incorrect aria description in List View
PR24516 -  Fix regression bug for category select in QueryControls component
PR24478 -  Fix tiny editor preview when using Mobile or Tablet options with \ 
metaboxes enabled