CI: Pinning flake8-rst, last version raises incorrect errors

[datapythonista]

• closes CI: azure failing #24755
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

CC: @jreback @FHaase

[jreback]

just make >=0.6.0<=0.7.0 for now

[datapythonista]

done

[jreback]

cool. merge on pass.

[codecov]

Codecov Report

Merging #24756 into master will decrease coverage by 49.46%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master   #24756       +/-   ##
===========================================
- Coverage   92.38%   42.91%   -49.47%     
===========================================
  Files         166      166               
  Lines       52363    52363               
===========================================
- Hits        48376    22473    -25903     
- Misses       3987    29890    +25903

Flag	Coverage Δ
#multiple	?
#single	42.91% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/io/formats/latex.py	0% <0%> (-100%)	⬇️
pandas/core/categorical.py	0% <0%> (-100%)	⬇️
pandas/io/sas/sas_constants.py	0% <0%> (-100%)	⬇️
pandas/tseries/plotting.py	0% <0%> (-100%)	⬇️
pandas/tseries/converter.py	0% <0%> (-100%)	⬇️
pandas/io/formats/html.py	0% <0%> (-99.35%)	⬇️
pandas/core/groupby/categorical.py	0% <0%> (-95.46%)	⬇️
pandas/io/sas/sas7bdat.py	0% <0%> (-91.17%)	⬇️
pandas/io/sas/sas_xport.py	0% <0%> (-90.15%)	⬇️
pandas/core/tools/numeric.py	10.44% <0%> (-89.56%)	⬇️
... and 123 more

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[codecov]

Codecov Report

Merging #24756 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #24756   +/-   ##
=======================================
  Coverage   92.38%   92.38%           
=======================================
  Files         166      166           
  Lines       52363    52363           
=======================================
  Hits        48376    48376           
  Misses       3987     3987

Flag	Coverage Δ
#multiple	90.81% <ø> (ø)	⬆️
#single	42.91% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f160c7d...3664cbf. Read the comment docs.

[jreback]

requirements-dev.txt(,): error : `requirements-dev.txt` has to be generated with `ci/../scripts/generate_pip_deps_from_conda.py` after `environment.yml` is modified.
Bash exited with code '1'.

[datapythonista]

Just saw it, luckily the syntax for >= and <= seems to be the same in pip as in conda, will push in a second, after I finish testing.