Doctest: Make Expression normalization work with symbolic powers

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Expression normalization only works with standard polynomials:

sage: (x^2 + x^(-2) - 2).normalize()
(x^4 - 2*x^2 + 1)/x^2

vs

sage: (x^(2*pi) + x^(-2*pi) - 2).normalize()
x^(2*pi) + x^(-2*pi) - 2

also (for different reasons):

sage: (e^2 + e^(-2) - 2).normalize()
e^2 + e^(-2) - 2

sage: (e^(2*pi) - e^(-2*pi)).normalize()
e^(2*pi) - e^(-2*pi)

This is necessary for being able to factor all symbolic expressions.

Depends on #23950

Component: symbolics

Author: Ralf Stephan

Branch/Commit: 824a54a

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/23861

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Description changed:

--- 
+++ 
@@ -8,6 +8,14 @@
 
 sage: (x^(2*pi) + x^(-2*pi) - 2).normalize()
 x^(2*pi) + x^(-2*pi) - 2
+
+also (for different reasons):
+
+sage: (e^2 + e^(-2) - 2).normalize()
+e^2 + e^(-2) - 2
+
+sage: (e^(2*pi) - e^(-2*pi)).normalize()
+e^(2*pi) - e^(-2*pi)
 ```
 
 This is necessary for being able to factor all symbolic expressions.

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Upstream: Fixed upstream, in a later stable release.

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Dependencies: pynac-0.7.12

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Changed dependencies from pynac-0.7.12 to #23950

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Changed upstream from Fixed upstream, in a later stable release. to none

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Branch: u/rws/23861

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Commit: 824a54a

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New commits:

824a54a

23861: Doctest fix for Expression normalization with symbolic powers

[rwst]

Author: Ralf Stephan