fix: memory issues in `counting_sort.cpp`

Description of Change

There are several problems with the current implementation of counting_sort.cpp:

• memory allocated by creating *Count is uninitialized and not deleted, https://github.com/TheAlgorithms/C-Plus-Plus/blob/23b133ae1eac4ad7e94e74da140d462180738413/sorting/counting_sort.cpp#L29
• memory allocated by creating *Sorted_Arr is not deleted. https://github.com/TheAlgorithms/C-Plus-Plus/blob/23b133ae1eac4ad7e94e74da140d462180738413/sorting/counting_sort.cpp#L27

This PR fixes that.

Checklist

• [x] Added description of change
• [x] PR title follows semantic commit guidelines
• [x] Search previous suggestions before making a new one, as yours may be a duplicate.
• [x] I acknowledge that all my contributions will be made under the project's license.

Notes: This PR fixes memory issues in counting_sort.cpp.

This pull request has been automatically marked as abandoned because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

@Panquesito7, @realstealthninja: please dont-close.