3238 broader system db support

[visch]

• Add a max string length to migrations
• Added a string limit to JSONEncodedDict
• Improve CLI performance by deferring imports (Improve CLI performance by avoiding unnecessary imports meltano/meltano#6186)
• Fix typo exceptions_context -> exception_context (Fix typo exceptions_context -> exception_context meltano/meltano#6212)
• Update debugging advice in contributor API doc (Update debugging advice in contributor API doc meltano/meltano#6211)
• Release v2.0.3 (Release v2.0.3 meltano/meltano#6215)
• Replace all with to fix pipeline running bug (fix: failing Meltano UI schedule execution due to stateID jobID renames meltano/meltano#6216)
• Add telemetry for meltano config (Add telemetry for meltano config meltano/meltano#6137)
• Add telemetry page to contributing docs (Add telemetry page to contributing docs meltano/meltano#6214)
• feat: Add meltano lock (feat: Add meltano lock meltano/meltano#6114)
• 3473 virtualenv advanced concept (3473 virtualenv advanced concept meltano/meltano#5964)
• Fire exit event exactly once & include detailed exception context (Fire exit event exactly once & include detailed exception context meltano/meltano#6203)
• job-id to job_id in migration guide (job-id to job_id in migration guide meltano/meltano#6228)
• Resolve intermittent errors when calling meltano config airflow (Resolve intermittent errors when calling meltano config airflow  meltano/meltano#6227)
• Add tracking for job command (Add tracking for job command meltano/meltano#6141)
• Virtual Environments broken links, and a few grammar improvements (Virtual Environments broken links, and a few grammar improvements meltano/meltano#6231)
• Restore project_id from analytics.json & improve analytics.json handling (Restore project_id from analytics.json & improve analytics.json handling meltano/meltano#6199)
• Fix Product Roadmap Action (Fix Product Roadmap Action meltano/meltano#6232)
• Release v2.1.0 (Release v2.1.0 meltano/meltano#6235)
• Update workflow to add assignment column (Update workflow to add assignment column meltano/meltano#6245)
• ci: Test Meltano on latest Python 3.9 in GitLab CI (ci: Test Meltano on latest Python 3.9 in GitLab CI meltano/meltano#5929)
• Windows CI test added to gitlab, Windows Docs added for installation (Windows CI test added to gitlab, Windows Docs added for installation meltano/meltano#5967)
• Remove old oppty assessment issue template. (Remove old oppty assessment issue template. meltano/meltano#6241)
• Permit null exit code in exit events (Permit null exit code in exit events meltano/meltano#6244)
• fix: Update Assign to Project action to use GitHub supported flavor (fix: Update Assign to Project action to use GitHub supported flavor meltano/meltano#6254)
• ci: Add Postgres tests to matrix (ci: Add Postgres tests to matrix meltano/meltano#6251)
• Add badges to README.md (Add badges to README.md meltano/meltano#6259)
• Run isort & clean-up tox.ini (Run isort & clean-up tox.ini meltano/meltano#6261)
• docs: Fix link in coverage badge (docs: Fix link in coverage badge meltano/meltano#6263)
• Fix changelog link in Meltano UI when update is available (fix(ui): fix stale 'update' link in Meltano UI meltano/meltano#6265)
• Conditionally include context with telemetry state change event (Conditionally include context with telemetry state change event meltano/meltano#6225)
• Fixed typing to work with MSSQL backends
• Added two more dynamic datetime types
• ci: Use docker run instead of services (ci: Use docker run instead of services meltano/meltano#6268)
• Altered migrations to work with MYSQL
• Added MSSQL testing to Github workflow
• Added MySQL to the Github workflow
• Hard coded string lengths in migrations
• Moved MSSQL testing to github action run
• Moved Mysql to Github run action
• Added MSSQL user to health check
• Install extra database drivers in testing action
• Added extras for database drivers
• Updated mysql auth in Github action
• Changed MSSQL driver to pymssql
• Added more string limits for MySQL