test: add user reference matrix

[ShabiShett07]

none

Description

What is the purpose of this pull request?

This pull request:

• Adds "C_mat" in a text fixture that was missing.

Related Issues

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This pull request:

• none

Questions

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No.

Other

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No.

Checklist

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• Read, understood, and followed the contributing guidelines.

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Coverage Report

Package	Statements	Branches	Functions	Lines
blas/base/ggemm	$\color{red}1326/1335$ $\color{green}+99.33\%$	$\color{red}172/175$ $\color{green}+98.29\%$	$\color{green}14/14$ $\color{green}+100.00\%$	$\color{red}1326/1335$ $\color{green}+99.33\%$

The above coverage report was generated for the changes in this PR.