fix: do not use nan in htsinfer call

[ninsch3000]

Description

Don't keep default nan when reading samples table in htsinfer.smk, otherwise nan will be used instead of empty string in call to htsinfer.

Fixes #135

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

Conventional Commits guidelines

• I made sure the PR title follows the
  https://www.conventionalcommits.org/en/v1.0.0/

Changes to workflow inputs (sample table and/or configs)

• major (add BREAKING CHANGE: in the beginning of the PR title)
  • more fields/properties are required
  • existing ones are dropped entirely
• minor (add feat: in the beginning of the PR title)
  • optional fields/properties are added
  • required ones are made optional

Changes to workflow outputs

• major (add BREAKING CHANGE: in the beginning of the PR title)
  • changes lead to removal/change of existing outputs (format or location)
• minor (add feat: in the beginning of the PR title)
  • additional outputs are generated
  • content (but not format or location) of existing outputs changes

Everything else: patch
(add any other conventional commit in the beginning of the PR title)

Checklist:

• My code changes follow the style of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing tests pass locally with my changes
• I have updated the project's documentation

[balajtimate]

Tested it with sample table with NaN entries and it fixed the issue.