fix memory leak

[thechampagne]

Please check if the PR fulfills these requirements

• The PR has no duplicates (please search among the Pull Requests
  before creating one)
• Tests for the changes have been added (for bug fixes / features)

• What kind of change does this PR introduce?

• What is the current behavior?

• What is the new behavior?

• Does this PR introduce a breaking change?

• Other information:

[CLAassistant]

All committers have signed the CLA.

[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (e740ad9) 17.76% compared to head (f19f336) 18.37%.
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #837      +/-   ##
==========================================
+ Coverage   17.76%   18.37%   +0.60%     
==========================================
  Files          53       53              
  Lines        4103     4120      +17     
==========================================
+ Hits          729      757      +28     
+ Misses       3270     3257      -13     
- Partials      104      106       +2     

Flag	Coverage Δ
unit	18.37% <ø> (+0.60%)	⬆️

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see 8 files with indirect coverage changes

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[umbynos]

Hello @thechampagne, thanks for your contribution! Could you please add a bit more context to this? It would make the review process a lot faster.
It seems that the CI is failing because it cannot build on macos. Could you please take a look at it?

[umbynos]

Hello @thechampagne, one last thing, and I think we are ready to merge: could you please run go fmt github.com/arduino/arduino-create-agent/certificates github.com/arduino/arduino-create-agent/systray. It seems that the CI is failing

[umbynos]

Thanks a lot for your contribution!

[ubidefeo]

I have tested this on Mac OS Ventura.
The app is able to generate certificates once the password is correctly entered by the user.
(it prompts for it)