fix(bundler) missing newline in deb desktop file generation (fix: #899, #925)

[ho-ho-ho]

What kind of change does this PR introduce? (check at least one)
fixes #899 and #925

• Bugfix
• Feature
• New Binding Issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes. Issue #___
• No

The PR fulfills these requirements:

• When resolving a specific issue, it's referenced in the PR's title (e.g. fix: #xxx[,#xxx], where "xxx" is the issue number)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Other information:
the generated desktop file didn't work properly (especially if no short_description was given) since the newline was missing and the next line ended up as a category.

[jbolda]

Thanks! Would you please add a change file as well?

[ho-ho-ho]

Sure, I think this should do it :)

[jbolda]

Cheers! Thanks!