BUG: fix dirint KeyError with scalar inputs on pandas >= 2.0

Author: Omesh37

pvlib/irradiance.py

@@ -2109,6 +2109,14 @@ def _dirint_bins(times, kt_prime, zenith, w, delta_kt_prime):
     -------
     tuple of kt_prime_bin, zenith_bin, w_bin, delta_kt_prime_bin
     """
+    # Ensure scalar inputs are converted to Series so that boolean masks
+    # produce a boolean Series rather than a scalar bool.
+    # Scalar bools cause KeyError in pandas >= 2.0. GH #XXXX
+    kt_prime = pd.Series(kt_prime, index=times, dtype=float)
+    zenith = pd.Series(zenith, index=times, dtype=float)
+    w = pd.Series(w, index=times, dtype=float)
+    delta_kt_prime = pd.Series(delta_kt_prime, index=times, dtype=float)
+
     # @wholmgren: the following bin assignments use MATLAB's 1-indexing.
     # Later, we'll subtract 1 to conform to Python's 0-indexing.