[GSoC] Functions: Fixes limit evaluations related to uppergamma and besselk function

[sachin-4099]

Fixes: #13571
Fixes: #14874

Brief description of what is fixed or changed

1. Adds _eval_is_meromorphic method and _eval_aseries to class lowergamma
2. Adds _eval_is_meromorphic method and _eval_rewrite_as_tractable method to class uppergamma
3. Rectifies eval method of class besselk

Other Comments

Regression Tests have been added.

Release Notes

• functions
  • Adds _eval_is_meromorphic method and _eval_aseries to class lowergamma
  • Adds _eval_is_meromorphic method and _eval_rewrite_as_tractable method to class uppergamma
  • Rectifies eval method of class besselk

[sympy-bot]

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• functions

  • Adds _eval_is_meromorphic method and _eval_aseries to class lowergamma (#19990 by @sachin-4099)

  • Adds _eval_is_meromorphic method and _eval_rewrite_as_tractable method to class uppergamma (#19990 by @sachin-4099)

  • Rectifies eval method of class besselk (#19990 by @sachin-4099)

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Fixes: #13571 
Fixes: #14874 

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

  1) Adds `_eval_is_meromorphic` method and  `_eval_aseries` to `class lowergamma` 
  2) Adds  `_eval_is_meromorphic` method and `_eval_rewrite_as_tractable` method to `class uppergamma`
  3) Rectifies `eval` method of `class besselk`


#### Other Comments
Regression Tests have been added.


#### Release Notes


<!-- BEGIN RELEASE NOTES -->
* functions
  * Adds `_eval_is_meromorphic` method and  `_eval_aseries` to `class lowergamma` 
  * Adds  `_eval_is_meromorphic` method and `_eval_rewrite_as_tractable` method to `class uppergamma`
  * Rectifies `eval` method of `class besselk`
<!-- END RELEASE NOTES -->

Update

The release notes on the wiki have been updated.

[codecov]

Codecov Report

Merging #19990 into master will increase coverage by 0.002%.
The diff coverage is 75.000%.

@@              Coverage Diff              @@
##            master    #19990       +/-   ##
=============================================
+ Coverage   59.579%   59.581%   +0.002%     
=============================================
  Files          669       669               
  Lines       173475    173498       +23     
  Branches     40911     40915        +4     
=============================================
+ Hits        103355    103373       +18     
- Misses       64266     64269        +3     
- Partials      5854      5856        +2     

[jksuom]

Thanks, looks good.