[brew] Cask validation fails when brew is disabled

[aalmiray]

java.lang.NullPointerException: Cannot invoke "String.contains(java.lang.CharSequence)" because "this.name" is null
	at org.jreleaser.model.Cask.getResolvedCaskName(Cask.java:92)
	at org.jreleaser.model.validation.BrewValidator.lambda$postValidateBrew$4(BrewValidator.java:211)
	at java.base/java.util.stream.Collectors.lambda$groupingBy$53(Collectors.java:1135)
	at java.base/java.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:169)
	at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179)
	at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133)
	at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
	at org.jreleaser.model.validation.BrewValidator.postValidateBrew(BrewValidator.java:211)
	at org.jreleaser.model.validation.DistributionsValidator.validateDistributions(DistributionsValidator.java:70)
	at org.jreleaser.model.JReleaserModelValidator.validateModel(JReleaserModelValidator.java:62)
	at org.jreleaser.model.JReleaserModelValidator.validate(JReleaserModelValidator.java:47)
	at org.jreleaser.model.JReleaserContext.validateModel(JReleaserContext.java:152)
	at org.jreleaser.engine.context.ModelConfigurer.configure(ModelConfigurer.java:78)
	at org.jreleaser.engine.context.ContextCreator.create(ContextCreator.java:75)
	at org.jreleaser.cli.AbstractModelCommand.createContext(AbstractModelCommand.java:140)
	at org.jreleaser.cli.AbstractModelCommand.execute(AbstractModelCommand.java:82)
	at org.jreleaser.cli.AbstractCommand.call(AbstractCommand.java:76)
	at org.jreleaser.cli.AbstractModelCommand.call(AbstractModelCommand.java:46)
	at org.jreleaser.cli.AbstractCommand.call(AbstractCommand.java:37)
	at picocli.CommandLine.executeUserObject(CommandLine.java:1953)
	at picocli.CommandLine.access$1300(CommandLine.java:145)
	at picocli.CommandLine$RunLast.executeUserObjectOfLastSubcommandWithSameParent(CommandLine.java:2352)
	at picocli.CommandLine$RunLast.handle(CommandLine.java:2346)
	at picocli.CommandLine$RunLast.handle(CommandLine.java:2311)
	at picocli.CommandLine$AbstractParseResultHandler.execute(CommandLine.java:2179)
	at picocli.CommandLine.execute(CommandLine.java:2078)
	at org.jreleaser.cli.Main.execute(Main.java:73)
	at org.jreleaser.cli.Main.run(Main.java:59)
	at org.jreleaser.cli.Main.main(Main.java:51)