sparkxgb 0.2.1

sparkxgb 0.2

Avoids sending two deprecated parameters to XGBoost. The default arguments in the R function are NULL, and it will return an error message if the call intends to use them:
- Sketch EPS - No longer supported since XGBoost version 1.6
- Timeout Request Updates - No long supported since XGBoost version 1.7
Adds setMissing param handler for XGBoostRegressor in the Scala code. The missing parameter in xgboost_regressor() was not working.
Creates the JAR for Scala version 2.12 only. The code is simple enough that it does not seem to need multiple Spark version compiling. This also means that Scala 2.11 is not supported at this time.

Modernizes the entire testthat suite, it also expands it to provide more coverage
Modernizes and expands CI testing. The single CI job is now expanded to three:
- R package check, with no testing against the three major OS's
- testthat tests against Spark version 3.5
- Coverage testing, also against Spark version 3.5
Removes forge dependency
Improves download, preparation and building of the JAR
Improves and cleans up the code that selects the JAR and Maven package to use. It now depends on a text file created by the script the updates the JARS.
Updates Roxygen and testthat versions
Edgar Ruiz (https://github.com/edgararuiz) will be the new maintainer of this package moving forward.

sparkxgb is a sparklyr extension that provides an interface to XGBoost on Spark.