Increase test coverage (90%)

[aelsayed95]

For #351

Describe your changes

• Adds integration tests for tree, stats and summary commands
• Adds unit tests for the stats command
• Raises minimum required coverage to --cov-fail-under=90

Testing performed
Ran tests and make pycoverage: the above commands are now at 100% coverage (but not the related reporters).

Total coverage: 93%

---------- coverage: platform linux, python 3.10.11-final-0 ----------
Name                                                 Stmts   Miss Branch BrPart  Cover   Missing
------------------------------------------------------------------------------------------------
src/memray/__main__.py                                   4      0      2      1    83%   5->exit
src/memray/_ipython/flamegraph.py                       65      3     14      3    92%   102, 131, 138
src/memray/commands/attach.py                          160     69     64     12    50%   97->103, 101, 106-108, 119->123, 128-156, 161-163, 178-185, 188-190, 205-206, 209-219, 301-306, 311, 325-326, 343, 353, 367-383
src/memray/commands/common.py                           93      9     26      5    88%   14, 36, 47, 53, 63, 130->133, 134-143
src/memray/commands/live.py                             43      8     22      5    74%   91, 96->100, 110, 112, 115-119
src/memray/commands/run.py                             155     15     62      9    88%   46, 82-93, 98->100, 101, 122-124, 127-129, 137, 139->142, 181, 307, 314, 317
src/memray/commands/transform.py                        39      3     12      5    84%   37, 46->exit, 53, 55, 64->72
src/memray/reporters/flamegraph.py                     123      7     36      8    89%   110-113, 120->122, 122->125, 159->161, 161->164, 170, 189->192, 205, 232
src/memray/reporters/stats.py                           95      2     41      2    97%   89, 135
src/memray/reporters/table.py                           33      1      6      1    95%   67
src/memray/reporters/transform.py                       52      1     14      1    97%   82
src/memray/reporters/tui.py                            235      2     62      1    99%   58, 374
tests/integration/misbehaving_extension/setup.py        10     10      2      0     0%   1-12
tests/integration/multithreaded_extension/main.py        8      8      2      0     0%   1-13
tests/integration/multithreaded_extension/setup.py      10     10      2      0     0%   1-12
tests/integration/test_api.py                           54      4     30      4    90%   73, 86, 93, 105
tests/integration/test_attach.py                        36      6     10      2    78%   58, 90-96, 100->exit
tests/integration/test_extensions.py                   169      3     46      0    99%   81-83
tests/integration/test_main.py                         450     36     38      7    91%   85-86, 94-103, 537->543, 1132-1137, 1251-1254, 1258-1261, 1268->exit, 1293-1296, 1306->exit, 1328-1329, 1356-1358, 1366->exit, 1390-1392, 1473
tests/integration/test_native_tracking.py              263      4    100      2    98%   247->254, 300-303
tests/integration/test_processes.py                     99     70     38      0    21%   27-30, 34-36, 42-74, 80-130, 136-161, 171-185
tests/integration/test_socket.py                       159      5     42      1    97%   136-139, 232
tests/integration/test_tracing.py                      529      2    174      4    99%   294, 999->exit, 1008->exit, 1022, 1036->exit, 1049->exit
tests/integration/test_tracking.py                     881     21    328     13    97%   79->77, 83, 138->136, 142, 176->174, 180, 220-221, 393->391, 397, 1484, 1542-1558, 1647->exit, 1668->exit
tests/unit/test_reader.py                               42      1     16      0    98%   64
tests/unit/test_stats_reporter.py                       74     21     18      0    66%   22-62
tests/unit/test_tracker.py                              18      2     12      2    87%   18, 33
tests/utils.py                                          72     17     26      2    72%   33-47, 81, 86, 96-100
------------------------------------------------------------------------------------------------
TOTAL                                                 6511    340   1582     90    93%

33 files skipped due to complete coverage.

Required test coverage of 90% reached. Total coverage: 93.33%

======================== 542 passed in 85.08s (0:01:25) ========================

Additional context
Add any other context about your contribution here.

[godlygeek]

LGTM