Superfile doesn't render small text files

[jkrshnmenon]

Describe the bug The function isTextFile in src/internal/string_function.go returns false even if the file contains printable characters only.

To Reproduce Steps to reproduce the behavior:

1. Create a file with the command echo "A" > /tmp/test
2. Use spf to open the /tmp directory and seek to the test file
3. The pane on the right will show the Unsupported formats error

Expected behavior A normal rendering of the file contents

System information (please complete the following information):

• OS: Ubuntu
• Version 22.04
• Superfile Version v1.1.3