ci: update versions of checkout and codecov actions

[grondo]

Problem: Github is reporting that Nodejs 12 actions are deprecated. This includes the checkout@v2 and codecov-action@v1 actions.

Update these actions to the latest versions, matching what was done in flux-core.

[codecov[bot]]

Codecov Report

Merging #69 (1474fa7) into main (71c4240) will increase coverage by 0.27%. The diff coverage is n/a.

:exclamation: Current head 1474fa7 differs from pull request most recent head 7ff5b84. Consider uploading reports for the commit 7ff5b84 to get more accurate results

@@            Coverage Diff             @@
##             main      #69      +/-   ##
==========================================
+ Coverage   79.10%   79.38%   +0.27%     
==========================================
  Files          10       10              
  Lines        1211     1227      +16     
==========================================
+ Hits          958      974      +16     
  Misses        253      253              

Impacted Files	Coverage Δ
src/shell/plugins/infovec.c	93.91% <0.00%> (ø)
src/shell/plugins/main.c	80.34% <0.00%> (+0.11%)	:arrow_up:
src/shell/plugins/abort.c	86.95% <0.00%> (+0.19%)	:arrow_up:
src/shell/plugins/codec.c	70.29% <0.00%> (+0.19%)	:arrow_up:
src/shell/plugins/interthread.c	83.09% <0.00%> (+0.24%)	:arrow_up:
src/shell/plugins/dmodex.c	81.31% <0.00%> (+0.41%)	:arrow_up:
src/shell/plugins/fence.c	84.54% <0.00%> (+0.43%)	:arrow_up:
src/shell/plugins/notify.c	88.46% <0.00%> (+0.46%)	:arrow_up:
src/shell/plugins/exchange.c	70.11% <0.00%> (+0.52%)	:arrow_up:

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[garlick]

Rebased this on current master and...uh oh, this again:

expecting success: 
    run_timeout 30 flux mini run -N1 -n2 \
        ${BARRIER} --timeout=2

  fkdhs3d.0: completed PMIx_Init.
  fkdhs3d.1: PMIx_Fence: TIMEOUT
  fkdhs3d.0: there are 2 tasks
  fkdhs3d.0: completed barrier in 0.003s.
  fkdhs3d.0: completed PMIx_Finalize.
  0.106s: flux-shell[0]:  WARN: pmix: unknown optional fence attr: pmix.timeout
  0.106s: flux-shell[0]:  WARN: pmix: unknown optional fence attr: pmix.sorted.parr
  flux-job: task(s) exited with exit code 1
  not ok 3 - 1n2p barrier tolerates pmix.timeout=2

also I accidentally merged the tmate ci hook.

[grondo]

also I accidentally merged the tmate ci hook.

Well that's a good thing! We can use it to debug.

[garlick]

Huh, why did mergify close this? Edit: my bad, I referenced this is in a Fixes line.

[garlick]

Rebased on current master.