Refresh the cache when filtering plus other minor changes

[manuelma]

Fixes #226, #228, #229

Checklist before merging

• [x] Documentation (also in Toolbox repo) is up-to-date
• [x] Release notes in Toolbox repo have been updated
• [x] Unit tests have been added/updated accordingly
• [x] Code has been formatted by black
• [x] Unit tests pass

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (c6aa34c) 75.46% compared to head (3b0cd77) 75.47%.

:exclamation: Current head 3b0cd77 differs from pull request most recent head 1f65bc0. Consider uploading reports for the commit 1f65bc0 to get more accurate results

:mega: This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #227 +/- ## ======================================= Coverage 75.46% 75.47% ======================================= Files 76 76 Lines 10862 10866 +4 Branches 2351 2353 +2 ======================================= + Hits 8197 8201 +4 Misses 2241 2241 Partials 424 424 ``` | [Impacted Files](https://codecov.io/gh/spine-tools/Spine-Database-API/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spine-tools) | Coverage Δ | | |---|---|---| | [spinedb\_api/db\_mapping\_remove\_mixin.py](https://codecov.io/gh/spine-tools/Spine-Database-API/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spine-tools#diff-c3BpbmVkYl9hcGkvZGJfbWFwcGluZ19yZW1vdmVfbWl4aW4ucHk=) | `96.55% <ø> (ø)` | | | [spinedb\_api/db\_mapping\_base.py](https://codecov.io/gh/spine-tools/Spine-Database-API/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spine-tools#diff-c3BpbmVkYl9hcGkvZGJfbWFwcGluZ19iYXNlLnB5) | `88.04% <100.00%> (+0.07%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spine-tools). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spine-tools)

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.