Update dependency mysql:mysql-connector-java to v5.1.21 - autoclosed

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

This PR contains the following updates:

Package	Type	Update	Change
mysql:mysql-connector-java	compile	patch	5.1.17 -> 5.1.21

By merging this PR, the below issues will be automatically resolved and closed:

Severity	CVSS Score	CVE	GitHub Issue
High	8.5	CVE-2017-3523	#6
High	8.3	CVE-2023-22102	#472

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