Adds some debug logging to selfupdate script.
Adds some debug logging to selfupdate script.

busches/gvm-cli,jbovet/gvm,shanman190/sdkman-cli,skpal/sdkman-cli,sdkman/sdkman-cli,skpal/sdkman-cli,GsusRecovery/sdkman-cli,GsusRecovery/sdkman-cli,gvmtool/gvm-cli