Replace deprecated build-helper:remove-project-artifact goal

[Stephan202]

Suggested commit message:

Replace deprecated `build-helper:remove-project-artifact` goal (#1413)

This resolves the following warning:

 [WARNING]  Goal 'remove-project-artifact' is deprecated: There is a similar goal: dependency:purge-local-repository <https://maven.apache.org/plugins/maven-dependency-plugin/purge-local-repository-mojo.html> By the way such goal should by not used with Maven 3/4 anymore.

(As for whether such a goal should not be used at all: (a) there's no point in caching these artifacts, and (b) we know from internal projects that keeping such SNAPSHOTs around can hide project cycles. Not likely to happen with our simple Maven build setup, but still.)

Tested as follows:

# Install project into local repository.
$ mvn clean install -DskipTests -Dverification.skip
# ...
# Validate that artifacts are now present.
$ find ~/.m2/repository/tech/picnic/error-prone-support | wc -l
88
# Run new artifact removal command.
$ mvn dependency:purge-local-repository -DmanualInclude='${project.groupId}' -DresolutionFuzziness=groupId
# ...
# Validate that artifacts are now gone.
$ ls ~/.m2/repository/tech/picnic/error-prone-support
ls: cannot access '/home/myusername/.m2/repository/tech/picnic/error-prone-support': No such file or directory

[github-actions]

Looks good. No mutations were possible for these changes.
Mutation testing report by Pitest. Review any surviving mutants by inspecting the line comments under Files changed.

[github-actions]

Looks good. No mutations were possible for these changes.
Mutation testing report by Pitest. Review any surviving mutants by inspecting the line comments under Files changed.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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