CI/TST: Supply dtype to coo_matrix until scipy is fixed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them

Fixes CI for Windows 3.7 np1.6; regression in scipy 1.6.1 (https://github.com/scipy/scipy/issues/13585)

Alternative would be to pin build, wasn't sure which is prefered over the other. Will open tracking issue once the method is decided.
going to backport as well, ping on green. Windows 3.7 np1.6 was successful, failures look unrelated. Running again. /azp run <samp>
Azure Pipelines successfully started running 1 pipeline(s).<br>

</samp> @jreback - greenish

Failing test is `TestTimedeltas.test_to_timedelta_oob_non_nano`, I'm seeing this fail on the most recent commit to master as well.  > @jreback - greenish
> 
> Failing test is `TestTimedeltas.test_to_timedelta_oob_non_nano`, I'm seeing this fail on the most recent commit to master as well.

oh that's prob something we just merged cc @jbrockmendel  thanks @rhshadrach  @meeseeksdev backport 1.2.x > test_to_timedelta_oob_non_nano

will take a look