feat: mark users to be scanned a month after suspension/cancellation

Closes #47

See merge request !43

Still maintains an additional not logged in in a month check too.

Leaving 6 month values, at least for stats but may be reused in future.

Enable deletion of all 2y cancelled accounts

See merge request !42

fix: logging when licenses run out

See merge request !41

Change --really-do-this to --write

Closes #46

See merge request !40

Merge branch '44-update-mark-for-scan-to-set-ucam-mydrive-shared-action-to-scan-folders-rather-than-scan' into 'master'

Update mark for scan to set UCam.mydrive-shared-action to "scan-folders" rather than "scan"

Closes #44

See merge request !39

Fix pagesize for licensing API listing

Closes #43

See merge request !38

delete users who are suspended and have a clean drive scan result

Closes #41 and #42

See merge request !36

Python 3.9 required

See merge request !35

Resolve "User Sync Tool - Step 1 - read and write custom schema, and initiate scanning"

Closes #40

See merge request !34

Remove suspended members from groups

Closes sync-deploy#21 and #31

See merge request !31

Fix version history

See merge request !30

Switch to using Lookup API instead of Ibis client

Closes #35

See merge request !27

The review discovered that the sync tool, when run on production, would never
succeed because the membership list of some groups/institutions was so large
that the API response exceeded the size limit imposed by API Gateway (due to
Lookup API returning detailed lists of members). This commit refactors the code
to fetch group/institution membership for each user and use that to populate
the membership set for each group/institution.

Use Python 3.9 in Dockerfile as new Python features are now used.

Update version of Flake8 so the checks are compatible with the newer version
of Python.

Remove redundant function `_extract_uid()`.

Modify Flake8 configuration to exclude the standard set of folders used across
projects.

Add settings for Lookup API and API Gateway credentials.

Add Lookup API operations to replicate the LDAP operations for gathering
information about users, groups and institutions.

Remove LDAP sync code and related configuration code.

Remove LDAP configuration options from the example file.

Remove LDAP library as a requirement it is no longer needed.

Remove LDAP references from documentation.

Add information to the README about how to provide API Gateway credentials.

Add YAML versions of API Gateway credentials file to `.gitignore`.

Add check for lookup jd import default displayname

Closes #39

See merge request !29

Allow empty responses at the end of retrieving pages of objects from Google API

Closes #38

See merge request !28