try replacing unicode to fix R CMD CHECK

[jarbet]

Description

#188 fails the R CMD CHECK because of a unicode character in a create.heatmap example. Replacing the unicode character fixes the issue.

Closes #...

Checklist

• This PR does NOT contain PHI or germline genetic data. A repo may need to be deleted if such data is uploaded. Disclosing PHI is a major problem.

• This PR does NOT contain molecular files, compressed files, output files such as images (e.g. .png, .jpeg), .pdf, .RData, .xlsx, .doc, .ppt, or other non-plain-text files. To automatically exclude such files using a .gitignore file, see here for example.

• I have read the code review guidelines and the code review best practice on GitHub check-list.

• I have set up or verified the main branch protection rule following the github standards before opening this pull request.

• The name of the branch is meaningful and well formatted following the standards, using [AD_username (or 5 letters of AD if AD is too long)]-[brief_description_of_branch].

• I have added the major changes included in this pull request to the NEWS under the next release version or unreleased, and updated the date. I have also updated the version number in DESCRIPTION according to semantic versioning rules.

• Both R CMD build and R CMD check run successfully.

Testing Results

Case 1

# input code

Case 2

# input code