Use literal suffix print pow

[bjodah]

References to other Issues or PRs

This PR merges changes from master into gh-19710 and also adds a test to guard against future regressions (fixes gh-19710).

Brief description of what is fixed or changed

This PR supersedes gh-19710 (it just adds a merge commit and a commit adding a test).

Other comments

cc @mmohrhard

Release Notes

• printing
  • Use literal suffix for 1.0 in C89CodePrinter's printing of pow when the exponent is -1

[sympy-bot]

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• printing
  • Use literal suffix for 1.0 in C89CodePrinter's printing of pow when the exponent is -1 (#19956 by @bjodah and @mmohrhard)

This will be added to https://github.com/sympy/sympy/wiki/Release-Notes-for-1.7.

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<!-- Your title above should be a short description of what
was changed. Do not include the issue number in the title. -->

#### References to other Issues or PRs
This PR merges changes from master into gh-19710 and also adds a test to guard against future regressions (fixes gh-19710).
<!-- If this pull request fixes an issue, write "Fixes #NNNN" in that exact
format, e.g. "Fixes #1234" (see
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write a comment on that issue linking back to this pull request once it is
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#### Brief description of what is fixed or changed
This PR supersedes gh-19710 (it just adds a merge commit and a commit adding a test).

#### Other comments
cc @mmohrhard 

#### Release Notes
<!-- Write the release notes for this release below. 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 -->
* printing
  * Use literal suffix for 1.0 in C89CodePrinter's printing of pow when the exponent is -1
<!-- END RELEASE NOTES -->

Update

The release notes on the wiki have been updated.

[eric-wieser]

Thanks!

[codecov]

Codecov Report

Merging #19956 into master will decrease coverage by 0.009%.
The diff coverage is 100.000%.

@@              Coverage Diff              @@
##            master    #19956       +/-   ##
=============================================
- Coverage   75.788%   75.778%   -0.010%     
=============================================
  Files          668       668               
  Lines       173201    173202        +1     
  Branches     40844     40844               
=============================================
- Hits        131266    131250       -16     
- Misses       36220     36235       +15     
- Partials      5715      5717        +2