Atol and Btol in scipy lsqr

[mrava87]

Problem

From version 1.8.0 scipy's atol and btol for scipy.sparse.linalg.lsqr have been changed from 1e-8 to 1e-6. Since we usually do not specify them in our test suite when using lsqr, some of our tests started failing (see https://github.com/PyLops/pylops/issues/325).

Completed

For the moment atol and btol have been fixed to the previous value (1e-8) in all tests that are failing. We however want this to propagate to all tests to avoid problems in future