This fixes a bug where values would not be trimmed before parsing them. That resulted in a value like " 2" being invalid, even though it's a perfectly fine number.
Because the frontend sends the filters for projects and other values with comma-separated spaces like "1, 2, 3", this essentially broke filtering by these values.
Resolves https://kolaente.dev/vikunja/vikunja/issues/2547
38c30d1eee