fix: new line making words together

[tairosonloa]

Problem

When exporting notes, new line characters were being replaced by an empty string. This was making words before and after the \n being together. Example:

# In the book

This is an annotation
inside a paragraph

# Before my changes (exported result)

This is an annotationinside a paragraph

# After my changes

This is an annotation inside a paragraph

Note how annotation and inside were wrongly being exported together (without space) prior to my changes.

Changes

• Replaces "\n" by " " instead of ""
• Removes unused deps (just did a go mod tidy)