Add absorbance unit and dimension (#2115)

Author: nneskildsf

CHANGES

@@ -10,6 +10,7 @@ Pint Changelog
 - Update constants to CODATA 2022 recommended values. (#2049)
 - Fixed issue with `.to_compact` and Magnitudes with uncertainties / Quantities with units (PR #2069, issue #2044)
 - Add conductivity dimension. (#2112)
+- Add absorbance unit and dimension. (#2114)
 
 
 0.24.4 (2024-11-07)

pint/default_en.txt

@@ -499,6 +499,10 @@ nuclear_magneton = e * hbar / (2 * m_p) = µ_N = mu_N
 [refractive_index] = []
 refractive_index_unit = [] = RIU
 
+# Absorbance
+[absorbance] = []
+absorbance_unit = [] = AU
+
 # Logaritmic Unit Definition
 #  Unit = scale; logbase; logfactor
 #  x_dB = [logfactor] * log( x_lin / [scale] ) / log( [logbase] )