SafeStatus and SafeLastStatus accept blank enabled_modules

[moisses89]

What was wrong?

LastSafeStatus required enabled_modules always, this field should be optional.

How was it fixed?

Configuring the model SafeStatus.enabled_modules blank=True to accept empty values.

[github-actions]

CLA Assistant Lite bot:
Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

---

I have read the CLA Document and I hereby sign the CLA

---

_{You can retrigger this bot by commenting recheck in this Pull Request}

[coveralls]

Pull Request Test Coverage Report for Build 2371018765

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 88.086%

---

Totals
Change from base Build 2359223568:	0.0%
Covered Lines:	5708
Relevant Lines:	6480

---

💛 - Coveralls