Fix power rules to fix some of the broken tests in CAS

[gkronber]

Bugfix in diff(x^n, x) rule and prevent folding 0^0 as well as negative to non-integer power

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.25%. Comparing base (e9aefa6) to head (5e5e912).

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Additional details and impacted files

@@             Coverage Diff             @@
##           ale/3.0     #252      +/-   ##
===========================================
+ Coverage    81.12%   81.25%   +0.13%     
===========================================
  Files           18       18              
  Lines         1499     1499              
===========================================
+ Hits          1216     1218       +2     
+ Misses         283      281       -2     

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Benchmark Results

	egg-sym	egg-cust	MT@5e5e912b86c...	MT@e9aefa6e6ea...	egg-sym/MT@5e5...	egg-cust/MT@5e...	MT@e9aefa6e6ea...
egraph_addexpr	1.45 ms		5.12 ms	5.12 ms	0.283		1
basic_maths_simpl2	12.5 ms	5 ms	19.3 ms	19.2 ms	0.648	0.259	0.995
prop_logic_freges_theorem	2.49 ms	1.53 ms	1.04 ms	1.04 ms	2.4	1.47	1
calc_logic_demorgan	61.1 μs	34.8 μs	74.7 μs	74.9 μs	0.817	0.465	1
calc_logic_freges_theorem	21.6 ms	11.8 ms	41 ms	40.9 ms	0.527	0.287	0.999
basic_maths_simpl1	6 ms	2.75 ms	4.68 ms	4.56 ms	1.28	0.589	0.975
egraph_constructor	0.0818 μs		0.0901 μs	0.0893 μs	0.907		0.99
prop_logic_prove1	34.7 ms	13.7 ms	41.2 ms	40.2 ms	0.841	0.332	0.974
prop_logic_demorgan	79.2 μs	44.2 μs	94 μs	93.5 μs	0.843	0.47	0.995
while_superinterpreter_while_10			18 ms	18.2 ms			1.01
prop_logic_rewrite			121 μs	120 μs			0.992
time_to_load			113 ms	113 ms			1

Benchmark Plots

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