compatibility with numpy>=2.0 (#257)

* attempt to fix the upstream-dev CI

* replace `np.unicode_` with `np.str_`

* remove `PROMOTE_TO_OBJECT` entirely

.github/workflows/upstream-dev-ci.yaml

@@ -19,7 +19,7 @@ jobs:
   upstream-dev:
     name: upstream-dev
     runs-on: ubuntu-latest
-    if: ${{ contains( github.event.pull_request.labels.*.name, 'test-upstream') && github.event_name == 'pull_request' || github.event_name == 'workflow_dispatch' }}
+    if: ${{ (contains(github.event.pull_request.labels.*.name, 'test-upstream') && github.event_name == 'pull_request') || github.event_name == 'workflow_dispatch' }}
     defaults:
       run:
         shell: bash -l {0}

flox/xrdtypes.py

@@ -31,17 +31,6 @@ def __eq__(self, other):
 NINF = AlwaysLessThan()
 
 
-# Pairs of types that, if both found, should be promoted to object dtype
-# instead of following NumPy's own type-promotion rules. These type promotion
-# rules match pandas instead. For reference, see the NumPy type hierarchy:
-# https://docs.scipy.org/doc/numpy-1.13.0/reference/arrays.scalars.html
-PROMOTE_TO_OBJECT = [
-    {np.number, np.character},  # numpy promotes to character
-    {np.bool_, np.character},  # numpy promotes to character
-    {np.bytes_, np.unicode_},  # numpy promotes to unicode
-]
-
-
 def maybe_promote(dtype):
     """Simpler equivalent of pandas.core.common._maybe_promote