Release artefacts with MD5 checksum

[PhilippSalvisberg]

utPLSQL for SQL Developer releases on https://github.com/utPLSQL/utPLSQL-SQLDeveloper/releases should contain a MD5 checksum file.

For Some company policies require that.

[PhilippSalvisberg]

create on Linux

md5sum utplsql_for_SQLDev_0.3.0.zip > utplsql_for_SQLDev_0.3.0.zip.md5

create on macOS

md5 -r utplsql_for_SQLDev_0.3.0.zip > utplsql_for_SQLDev_0.3.0.zip.md5

[PhilippSalvisberg]

generate MD5 hash for the Maven package goal. See https://checksum-maven-plugin.nicoulaj.net/usage.html