Update dependency mysql:mysql-connector-java to v8

[dev-mend-for-github-com[bot]]

This PR contains the following updates:

Package	Type	Update	Change
mysql:mysql-connector-java	compile	major	5.1.48 -> 8.0.16

By merging this PR, the issue #15 will be automatically resolved and closed:

Severity	CVSS Score	CVE	Reachability
Medium	5.0	CVE-2020-2934
Medium	4.7	CVE-2020-2875
Medium	4.5	CVE-2019-2692
Low	2.2	CVE-2020-2933

---

• [ ] If you want to rebase/retry this PR, check this box