fix: Migrate away from deprecated pulp API (#2610)

### Description

The latest update of pulp 2.8.0 removed deprecated API calls still used
by snakemake.
This PR updates the calls to their modern equivalents, as well as
constrains the pulp version to the moment these got introduced (v2.3.1).

Fixes the issues described in #2607 and #2606.

### QC
<!-- Make sure that you can tick the boxes below. -->

* [x] The PR contains a test case for the changes or the changes are
already covered by an existing test case.
* [x] The documentation (`docs/`) is updated to reflect the changes or
this is not necessary (e.g. if the change does neither modify the
language nor the behavior or functionalities of Snakemake).

---------

Co-authored-by: Johannes Köster <johannes.koester@uni-due.de>

setup.cfg

@@ -46,7 +46,7 @@ install_requires =
     nbformat
     packaging
     psutil
-    pulp >=2.0
+    pulp >=2.3.1,<2.9 # pulp introduced a breaking change from 2.7 to 2.8. Hence we should always pin to the minor version.
     pyyaml
     requests
     reretry

snakemake/cli.py

@@ -767,7 +767,7 @@ def get_argument_parser(profiles=None):
     try:
         import pulp
 
-        lp_solvers = pulp.list_solvers(onlyAvailable=True)
+        lp_solvers = pulp.listSolvers(onlyAvailable=True)
     except ImportError:
         # Dummy list for the case that pulp is not available
         # This only happened when building docs.

snakemake/scheduler.py

@@ -607,7 +607,7 @@ def _solve_ilp(self, prob):
             )
         try:
             solver = (
-                pulp.get_solver(self.workflow.scheduling_settings.ilp_solver)
+                pulp.getSolver(self.workflow.scheduling_settings.ilp_solver)
                 if self.workflow.scheduling_settings.ilp_solver
                 else pulp.apis.LpSolverDefault
             )

test-environment.yml

@@ -39,7 +39,7 @@ dependencies:
   - jsonschema
   - pandas
   - gitpython
-  - pulp >=2.0
+  - pulp >=2.3.1
   - environment-modules
   - nbformat
   - toposort >=1.10