Various fixes for 1.11 release blocker issues

[oscarbenjamin]

References to other Issues or PRs

Fixes #23707
Fixes #23704
Partial fix for #23677

Brief description of what is fixed or changed

When unrad encounters an expression that is not a polynomial function of the contained radicals such as sqrt(x)*exp(t*sqrt(x)) it should give up.

Also a bug in Risch was fixed to handle empty subspaces.

A problem with numerical robustness in minpoly was also fixed.

Other comments

Release Notes

• solvers
  • A bug that caused an AttributeError when solving some equations or evaluating some integrals with radicals was fixed.
• integrals
  • A bug in the Risch integration algorithm was fixed. Previously certain integrals would fail with an exception if an intermediate step generated an empty subspace.
• polys
  • Numerical calculations in minpoly were made more robust fixing a bug that failed to compute the minimal polynomial for certain complicated algebraic expressions.

[sympy-bot]

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Hi, I am the SymPy bot (v167). I'm here to help you write a release notes entry. Please read the guide on how to write release notes.

Your release notes are in good order.

Here is what the release notes will look like:

• integrals

  • A bug in the Risch integration algorithm was fixed. Previously certain integrals would fail with an exception if an intermediate step generated an empty subspace. (#23717 by @oscarbenjamin)

• polys

  • Numerical calculations in minpoly were made more robust fixing a bug that failed to compute the minimal polynomial for certain complicated algebraic expressions. (#23717 by @oscarbenjamin)

• solvers

  • A bug that caused an AttributeError when solving some equations or evaluating some integrals with radicals was fixed. (#23717 by @oscarbenjamin)

This will be added to https://github.com/sympy/sympy/wiki/Release-Notes-for-1.11.

Click here to see the pull request description that was parsed.

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#### References to other Issues or PRs
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Fixes #23707
Fixes #23704
Partial fix for #23677

#### Brief description of what is fixed or changed

When `unrad` encounters an expression that is not a polynomial function of the contained radicals such as `sqrt(x)*exp(t*sqrt(x))` it should give up.

Also a bug in Risch was fixed to handle empty subspaces.

A problem with numerical robustness in `minpoly` was also fixed.

#### Other comments


#### Release Notes

<!-- Write the release notes for this release below between the BEGIN and END
statements. The basic format is a bulleted list with the name of the subpackage
and the release note for this PR. For example:

* solvers
  * Added a new solver for logarithmic equations.

* functions
  * Fixed a bug with log of integers.

or if no release note(s) should be included use:

NO ENTRY

See https://github.com/sympy/sympy/wiki/Writing-Release-Notes for more
information on how to write release notes. The bot will check your release
notes automatically to see if they are formatted correctly. -->

<!-- BEGIN RELEASE NOTES -->
* solvers
  * A bug that caused an AttributeError when solving some equations or evaluating some integrals with radicals was fixed.
* integrals
  * A bug in the Risch integration algorithm was fixed. Previously certain integrals would fail with an exception if an intermediate step generated an empty subspace.
* polys
  * Numerical calculations in `minpoly` were made more robust fixing a bug that failed to compute the minimal polynomial for certain complicated algebraic expressions.
<!-- END RELEASE NOTES -->

Update

The release notes on the wiki have been updated.

[github-actions]

Benchmark results from GitHub Actions

Lower numbers are good, higher numbers are bad. A ratio less than 1
means a speed up and greater than 1 means a slowdown. Green lines
beginning with + are slowdowns (the PR is slower then master or
master is slower than the previous release). Red lines beginning
with - are speedups.

Significantly changed benchmark results (PR vs master)

Significantly changed benchmark results (master vs previous release)

       before           after         ratio
     [77f1d79c]       [b64cfcdb]
     <sympy-1.10.1^0>                 
+      96.6±0.4ms        175±0.8ms     1.81  sum.TimeSum.time_doit

Full benchmark results can be found as artifacts in GitHub Actions
(click on checks at the top of the PR).

[oscarbenjamin]

This PR fixes 3 different release blocker issues that are all bugs and/or regressions.

Can someone review this?

[jksuom]

Looks good.

[oscarbenjamin]

Thanks @jksuom !