enable build with Maven 4

[hboutemy]

IT failure:

[INFO] -------------------------------------------------
[INFO] Build Summary:
[INFO]   Passed: 6, Failed: 1, Errors: 0, Skipped: 0
[INFO] -------------------------------------------------
[ERROR] The following builds failed:
[ERROR] *  use-custom-toolchain/pom.xml
[INFO] -------------------------------------------------

Caused by: java.lang.NoSuchMethodError: 'void org.apache.maven.toolchain.DefaultToolchain.<init>(org.apache.maven.toolchain.model.ToolchainModel, java.lang.String, org.codehaus.plexus.logging.Logger)'
    at org.apache.maven.plugins.toolchains.its.custom.CustomToolchainImpl.<init>(CustomToolchainImpl.java:37)
    at org.apache.maven.plugins.toolchains.its.custom.CustomToolchainFactory.createToolchain(CustomToolchainFactory.java:61)
    at org.apache.maven.toolchain.ToolchainManagerFactory$2.createToolchain(ToolchainManagerFactory.java:142)
    at org.apache.maven.impl.DefaultToolchainManager.createToolchain(DefaultToolchainManager.java:106)

to be fixed in Maven 4 apache/maven#11973