Poetry - Figure out the latest version which is compatible with other dependencies

Using poetry, sometimes when checking for dependency Poetry will indicate that you can't install something because of compatibility issues.

For example, I have on my project numpy==1.19.2. Now when I try to install pandas I get the following

$: poetry add pandas

The currently activated Python version 3.6.9 is not supported by the project (>=3.8,<3.11).
Trying to find and use a compatible version. 
Using python3.9 (3.9.7)
Using version ^1.3.4 for pandas

Updating dependencies
Resolving dependencies... (0.6s)

  SolverProblemError

  Because no versions of pandas match >1.3.4,<2.0.0
   and pandas (1.3.4) depends on numpy (>=1.20.0), pandas (>=1.3.4,<2.0.0) requires numpy (>=1.20.0).
  So, because my_project depends on both numpy (1.19.2) and pandas (^1.3.4), version solving failed.

How can I figure out which pandas version should I install to be compatible with my version of numpy?

Solution

If you execute a dry run of the pandas package addition with the * version qualifier it should resolve to the latest version that is compatible with your other dependencies:

poetry add pandas@* --dry-run

You will see the exact version of pandas that would be installed in the command output. You can then use that version to update the version qualifier in your pyproject.toml file.

Alternatively, use the * qualifier directly in the pyproject.toml file as follows:

[tool.poetry.dependencies]
...
pandas = "*"
...