* Remove double quotes from the logbackVersion property.
* Set (correct) core Spring Framework version to 5.2.23.
* Change 'javax.enterprise:cdi-api:1.0' to a 'provided' dependency required to compile the CDI supporting infrastructure and source code.
* Change 'ch.qos.logback:logback-classic' to a 'testImplementation' dependency required to compile test source code.
Resolves#623.