Update solvers (#434)

* Enable DDP training with batch_size=None and add validity check for split sizes
* Refactoring SolverInterfaces (#435)
* Solver update + weighting
* Updating PINN for 0.2
* Modify GAROM + tests
* Adding more versatile loggers
* Disable compilation when running on Windows
* Fix tests

---------

Co-authored-by: giovanni <giovanni.canali98@yahoo.it>
Co-authored-by: FilippoOlivo <filippo@filippoolivo.com>

pina/optim/optimizer_interface.py

@@ -1,7 +1,15 @@
 """ Module for PINA Optimizer """
 
-from abc import ABCMeta
+from abc import ABCMeta, abstractmethod
 
 
 class Optimizer(metaclass=ABCMeta):  # TODO improve interface
-    pass
+
+    @property
+    @abstractmethod
+    def instance(self):
+        pass
+
+    @abstractmethod
+    def hook(self):
+        pass