Migrate away from pivotal-legacy/homebrew-tap

Update formula to use spring-boot rather than springboot. This will
allow both taps to be used at the same time.

See gh-24659

spring-boot-project/spring-boot-cli/pom.xml

@@ -349,15 +349,15 @@
 									property="checksum" />
 								<echo
 									message="Customizing homebrew for ${project.version} with checksum ${checksum} in ${repo} repo" />
-								<copy file="${basedir}/src/main/homebrew/springboot.rb"
-									tofile="${project.build.directory}/homebrew/springboot.rb"
+								<copy file="${basedir}/src/main/homebrew/spring-boot.rb"
+									tofile="${project.build.directory}/homebrew/spring-boot.rb"
 									overwrite="true">
 									<filterchain>
 										<expandproperties />
 									</filterchain>
 								</copy>
 								<attachartifact
-									file="${project.build.directory}/homebrew/springboot.rb"
+									file="${project.build.directory}/homebrew/spring-boot.rb"
 									classifier="homebrew" type="rb" />
 							</target>
 						</configuration>

spring-boot-project/spring-boot-cli/src/main/homebrew/springboot.rb → spring-boot-project/spring-boot-cli/src/main/homebrew/spring-boot.rb

 require 'formula'
 
-class Springboot < Formula
+class SpringBoot < Formula
   homepage 'https://spring.io/projects/spring-boot'
   url 'https://repo.spring.io/${repo}/org/springframework/boot/spring-boot-cli/${project.version}/spring-boot-cli-${project.version}-bin.tar.gz'
   version '${project.version}'