CASSJAVA-67 Fixes to get "mvn release:prepare" back on track

[absurdfarce]

Note: all of the fixes here were developed by @adutra (who has apparently forgotten more about Maven than I'll ever know).

Broken into two commits (for now) to clearly decouple the fix for the initial problem as well as the (completely separate) fix for a follow-on problem @adutra discovered during testing.

[absurdfarce]

Note: this change actually fixes the "basedir... does not exist" issues originally described in the ticket.

[absurdfarce]

Note: this change (and the change above) are necessary to fix a follow-on issue observed after the "basedir... does not exist" issue was resolved by the change below:

[INFO] [INFO] --- javadoc:3.0.1:jar (attach-javadocs) @ cassandra-driver-dist ---
[INFO] [INFO] 
[INFO] [INFO] --- gpg:1.5:sign (sign-release-artifacts) @ cassandra-driver-dist ---
[INFO] [INFO] ------------------------------------------------------------------------
[INFO] [INFO] Reactor Summary for Java Driver for Apache Cassandra 3.11.6-SNAPSHOT:
[INFO] [INFO] 
[INFO] [INFO] Java Driver for Apache Cassandra ................... SUCCESS [  2.041 s]
[INFO] [INFO] Java Driver for Apache Cassandra - Core ............ SUCCESS [ 18.895 s]
[INFO] [INFO] Java Driver for Apache Cassandra - Object Mapping .. SUCCESS [  9.554 s]
[INFO] [INFO] Java Driver for Apache Cassandra - Extras .......... SUCCESS [  6.934 s]
[INFO] [INFO] Java Driver for Apache Cassandra - Examples ........ SUCCESS [  3.299 s]
[INFO] [INFO] Java Driver for Apache Cassandra Tests ............. SUCCESS [  0.419 s]
[INFO] [INFO] Java Driver for Apache Cassandra Tests - Stress .... SUCCESS [  1.742 s]
[INFO] [INFO] Java Driver for Apache Cassandra Tests - OSGi ...... SUCCESS [  0.081 s]
[INFO] [INFO] Java Driver for Apache Cassandra Tests - OSGi - Shaded SUCCESS [  1.009 s]
[INFO] [INFO] Java Driver for Apache Cassandra Tests - OSGi - Shaded SUCCESS [  1.175 s]
[INFO] [INFO] Java Driver for Apache Cassandra Tests - OSGi - Unshaded SUCCESS [  1.068 s]
[INFO] [INFO] Java Driver for Apache Cassandra Tests - Shading ... SUCCESS [  0.398 s]
[INFO] [INFO] Java Driver for Apache Cassandra Tests - Shading - Shaded SUCCESS [  0.655 s]
[INFO] [INFO] Java Driver for Apache Cassandra Tests - Shading - Unshaded SUCCESS [  0.652 s]
[INFO] [INFO] Apache Cassandra Java Driver - source distribution . SUCCESS [  0.911 s]
[INFO] [INFO] Java Driver for Apache Cassandra - Binary distribution FAILURE [  0.623 s]
[INFO] [INFO] ------------------------------------------------------------------------
[INFO] [INFO] BUILD FAILURE
[INFO] [INFO] ------------------------------------------------------------------------
[INFO] [INFO] Total time:  50.299 s
[INFO] [INFO] Finished at: 2024-12-26T13:41:48+01:00
[INFO] [INFO] ------------------------------------------------------------------------
[INFO] [ERROR] Failed to execute goal org.apache.maven.plugins:maven-gpg-plugin:1.5:sign (sign-release-artifacts) on project cassandra-driver-dist: The project artifact has not been assembled yet. Please do not invoke this goal before the lifecycle phase "package". -> [Help 1]
[INFO] [ERROR]