Fix missing maven-deploy and prerequisites Maven warnings

[abelsromero]

Thank you for opening a pull request and contributing to asciidoctor-maven-plugin!

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Documentation
• Refactor
• Build improvement
• Other (please describe)

What is the goal of this pull request?

Fix build warnings observed in my machine. In short, we needed to set the version for maven-deploy-plugin and place <prerequisites> in the actual maven plugin sub-module, not the root.

[WARNING] Some problems were encountered while building the effective model for org.asciidoctor:asciidoctor-maven-plugin:maven-plugin:3.0.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-deploy-plugin is missing. @ org.apache.maven:maven-model-builder:3.8.8:super-pom, jar:file:/home/asalgadr/.sdkman/candidates/maven/3.8.8/lib/maven-model-builder-3.8.8.jar!/org/apache/maven/model/pom-4.0.0.xml, line 137, column 19
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.asciidoctor:asciidoctor-converter-doxia-module:jar:3.0.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-deploy-plugin is missing. @ org.apache.maven:maven-model-builder:3.8.8:super-pom, jar:file:/home/asalgadr/.sdkman/candidates/maven/3.8.8/lib/maven-model-builder-3.8.8.jar!/org/apache/maven/model/pom-4.0.0.xml, line 137, column 19
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.asciidoctor:asciidoctor-parser-doxia-module:jar:3.0.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-deploy-plugin is missing. @ org.apache.maven:maven-model-builder:3.8.8:super-pom, jar:file:/home/asalgadr/.sdkman/candidates/maven/3.8.8/lib/maven-model-builder-3.8.8.jar!/org/apache/maven/model/pom-4.0.0.xml, line 137, column 19
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.asciidoctor:asciidoctor-maven-commons:jar:3.0.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-deploy-plugin is missing. @ org.apache.maven:maven-model-builder:3.8.8:super-pom, jar:file:/home/asalgadr/.sdkman/candidates/maven/3.8.8/lib/maven-model-builder-3.8.8.jar!/org/apache/maven/model/pom-4.0.0.xml, line 137, column 19
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.asciidoctor:asciidoctor-maven-tools:pom:3.0.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-deploy-plugin is missing. @ org.apache.maven:maven-model-builder:3.8.8:super-pom, jar:file:/home/asalgadr/.sdkman/candidates/maven/3.8.8/lib/maven-model-builder-3.8.8.jar!/org/apache/maven/model/pom-4.0.0.xml, line 137, column 19
[WARNING] 


[WARNING] The project org.asciidoctor:asciidoctor-maven-tools:pom:3.0.0-SNAPSHOT uses prerequisites which is only intended for maven-plugin projects but not for non maven-plugin projects. For such purposes you should use the maven-enforcer-plugin. See https://maven.apache.org/enforcer/enforcer-rules/requireMavenVersion.html

Also, fixed CHANGELOG.

Are there any alternative ways to implement this?

no

Are there any implications of this pull request? Anything a user must know?

n/a

Is it related to an existing issue?

• Yes
• No

Finally, please add a corresponding entry to CHANGELOG.adoc