Try to fix race condition in testing

[sroet]

Tests had a non-insignificant chance of failing due to this condition being triggerd.
I added a 1 sec wait between raising the error and seeing if all children are dead to hopefully solve this issue

[github-actions]

File	Coverage		Missing
All files	80%	✅
src/pytom_tm/angles.py	94%	✅	44
src/pytom_tm/correlation.py	85%	✅	94-95 126
src/pytom_tm/entry_points.py	68%	❌	27 104-121 283-342 431-445 542-557 791-858 899-910
src/pytom_tm/extract.py	73%	❌	107-118 170-176 202-205 277-295
src/pytom_tm/io.py	42%	❌	14-18 24-27 33-36 42-45 51-54 61-65 73-86 92-99 106-113 128-130 163 197-198 243-245 261 277 294-303 323-328
src/pytom_tm/mask.py	80%	✅	70 85 94-95
src/pytom_tm/matching.py	95%	✅	186-196 340
src/pytom_tm/parallel.py	84%	✅	14-15 81-87 95-97 104 109 148
src/pytom_tm/plotting.py	16%	❌	20-22 25-32 36-44 48-51 54-70 73-74 77-78 98-103 119-127 133-150 165-173 177-194 198-206 210-217 223 229 234 248-398
src/pytom_tm/template.py	57%	❌	57-58 67 76-87 92-97 107-112 114
src/pytom_tm/tmjob.py	96%	✅	170-171 183 189-191 194 327 367
src/pytom_tm/utils.py	78%	❌	16-18
src/pytom_tm/weights.py	95%	✅	59 290-291 298 477 480 483

Minimum allowed coverage is 79%

Generated by 🐒 cobertura-action against 67d8c2e

[McHaillet]

LGTM! I assume it fixes it, but if not we'll find out.