Update CHANGELOG.md for 12.8.0

[ci skip]

changelogs/unreleased/georgekoltsov-add-award-emoji-to-notes-of-epics.yml

----
-title: Add award emoji information of Epics and Epic Notes to Group Import/Export
-merge_request: 24003
-author:
-type: changed

changelogs/unreleased/georgekoltsov-add-board-lists.yml

----
-title: Add Board Lists to Group Export
-merge_request: 24863
-author:
-type: changed

changelogs/unreleased/georgekoltsov-add-epics-activity-to-group-export.yml

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-title: Add Epics Activity information to Group Export
-merge_request: 23613
-author:
-type: changed

changelogs/unreleased/georgekoltsov-filter-group-attributes.yml

----
-title: Extend the list of excluded_attributes for group on Group Import
-merge_request: 25031
-author:
-type: fixed

changelogs/unreleased/georgekoltsov-fix-group-import-visibility-level.yml

----
-title: Use closest allowed visibility level on group creation when importing groups
-  using Group Import/Export
-merge_request: 25026
-author:
-type: fixed

changelogs/unreleased/georgekoltsov-group-import-api.yml

----
-title: Add Group Import API endpoint & update Group Import/Export documentation
-merge_request: 20353
-author:
-type: added

changelogs/unreleased/georgekoltsov-object_builder_convert_empty_strings.yml

----
-title: Fix Group Import existing objects lookup when description attribute is an empty
-  string
-merge_request: 25187
-author:
-type: fixed

changelogs/unreleased/georgekoltsov-remove-name-path-from-group-ie-yml.yml

----
-title: Remove name & path from list of excluded attributes during Group Import
-merge_request: 25342
-author:
-type: fixed

changelogs/unreleased/georgekoltsov-remove-username-lookup-from-members-mapper.yml

----
-title: Remove username lookup when mapping users when importing projects using Project
-  Import/Export and rely on email only
-merge_request: 24464
-author:
-type: changed

changelogs/unreleased/get_deployments_for_kubernetes_1-16.yml

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-title: Stop NoMethodError happening for 1.16+ Kubernetes clusters
-merge_request: 23149
-author:
-type: fixed

changelogs/unreleased/gitaly-version-v1-83-0.yml

----
-title: Upgrade to Gitaly v1.83.0
-merge_request: 23431
-author:
-type: changed

changelogs/unreleased/gitaly-version-v1.85.0.yml

----
-title: Upgrade to Gitaly v1.85.0
-merge_request: 23945
-author:
-type: changed

changelogs/unreleased/gitaly-version-v1.86.0.yml

----
-title: Upgrade to Gitaly v1.86.0
-merge_request: 24610
-author:
-type: changed

changelogs/unreleased/gitaly-version-v1.87.0.yml

----
-title: Upgrade to Gitaly v1.87.0
-merge_request: 25370
-author:
-type: changed

changelogs/unreleased/gracefully-handle-duplicate-artifacts-uploads.yml

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-title: Replace artifacts via Runner API if already exist
-merge_request: 24165
-author:
-type: fixed

changelogs/unreleased/graphiql_relative_url.yml

----
-title: Add pages_access_level to projects API
-merge_request: 23176
-author: Mathieu Parent
-type: added

changelogs/unreleased/gt-move-clone-button-to-the-tree-controls-area.yml

----
-title: Move the clone button to the tree controls area
-merge_request: 17752
-author: Ablay Keldibek
-type: changed

changelogs/unreleased/i18n-groups-audit-events.yml

----
-title: Internationalize messages for group audit events
-merge_request: 25233
-author: Takuya Noguchi
-type: other

changelogs/unreleased/id-limit-blob-data-for-diffs.yml

----
-title: Load maximum 1mb blob data for a diff file
-merge_request: 24160
-author:
-type: performance

changelogs/unreleased/id-upload-lsif-dump.yml

----
-title: Add support for lsif artifact report
-merge_request: 23672
-author:
-type: added