Enforce labels on PRs

[blink1073]

References

Use the new action from maintainer-tools.

Code changes

Adds a workflow to ensure PRs are labeled with a triage label.

User-facing changes

None

Backwards-incompatible changes

None

[jupyterlab-probot]

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[blink1073]

I verified that the build fails when there is no label and passes when there is a label.

[fcollonval]

Awesome thanks a lot @blink1073

Approving as the new job is green and the others are not relevant here.

[blink1073]

@meeseeksdev please backport to 3.2.x

[github-actions]

Benchmark report

The execution time (in milliseconds) are grouped by test file, test type and browser.
For each case, the following values are computed: min <- [1st quartile - median - 3rd quartile] -> max.

The mean relative comparison is computed with 95% confidence.

Results table

Test file	large_code_notebook	large_md_notebook
open
chromium
actual	6316 <- [7079 - 7303 - 7886] -> 8817	3215 <- [3461 - 3687 - 4074] -> 4752
expected	6250 <- [7369 - 7570 - 7947] -> 9095	3177 <- [3447 - 3661 - 3889] -> 4652
Mean relative change	-2.4% ± 2.0%	1.7% ± 2.7%
switch-from
chromium
actual	792 <- [888 - 969 - 1146] -> 1508	520 <- [606 - 751 - 810] -> 1022
expected	813 <- [927 - 988 - 1199] -> 1666	510 <- [581 - 714 - 824] -> 973
Mean relative change	-2.9% ± 4.4%	1.8% ± 5.2%
switch-to
chromium
actual	843 <- [888 - 939 - 989] -> 1132	633 <- [749 - 784 - 832] -> 939
expected	864 <- [922 - 975 - 1021] -> 1284	630 <- [727 - 780 - 838] -> 943
Mean relative change	-3.9% ± 1.9%	1.0% ± 2.4%
close
chromium
actual	873 <- [969 - 1081 - 1372] -> 1572	584 <- [639 - 676 - 719] -> 835
expected	859 <- [992 - 1068 - 1419] -> 1625	579 <- [641 - 668 - 707] -> 884
Mean relative change	-0.8% ± 5.2%	1.1% ± 2.3%

Changes are computed with expected as reference.