Dcoraid

- fix: set row count to zero when all jobs are removed from upload queue
- enh: increase buffer size for uploads to 4MB

- setup: bump requests to 2.31.0 (CVE-2023-32681)
- setup: bump dclab from 0.50.2 to 0.52.0

- fix: properly propagate SystemExit exit codes

- fix: make CACHE_DIR an optional argument to dclab-upload-task

- fix: error message in preferences user tab no connection available
- enh: allow to select upload cache directory in CLI
- enh: allow to select upload cache directory in GUI
- enh: make sure temporary cache directories for uploads are removed
- enh: replace lru_cache with weak_lru_cache for instance methods
- setup: bump dclab from 0.49.0 to 0.50.2
- setup: bump urllib3 to 2.0
- setup: bump requests_toolbelt to 1.0

- setup: bump dclab from 0.48.4 to 0.49.0 (support tables)