gnu: python-pandas: Default to version 2.x.

* gnu/packages/python-science.scm (python-pandas): Define as alias for
python-pandas-2; rename existing definition to...
(python-pandas-1): ...this new variable.

Change-Id: If359e3b2d42c683d7d0152b1757bbc5a979c999b

gnu/packages/python-science.scm

@@ -748,7 +748,7 @@ spheres, cubes, etc.")
 tissue-specificity metrics for gene expression.")
     (license license:gpl3+)))
 
-(define-public python-pandas
+(define-public python-pandas-1
   (package
     (name "python-pandas")
     (version "1.5.3")
@@ -957,6 +957,8 @@ and intuitive.  It aims to be the fundamental high-level building block for
 doing practical, real world data analysis in Python.")
     (license license:bsd-3)))
 
+(define-public python-pandas python-pandas-2)
+
 (define-public python-pandas-stubs
   (package
     (name "python-pandas-stubs")