Move FindBugs dependency version management to gradle/dependency-management.gradle.

gradle.properties

@@ -1,7 +1,6 @@
 org.gradle.jvmargs=-Xmx2g -Dfile.encoding=UTF-8
 deployDocsHost=docs-ip.spring.io
 apacheGeodeVersion=1.14.4
-findbugsVersion=3.0.2
 springVersion=5.3.19
 springBootVersion=2.6.6
 springDataBomVersion=2021.1.4

gradle/dependency-management.gradle

@@ -4,6 +4,7 @@ ext['apacheTaglibsVersion'] = '1.2.5'
 ext['assertjVersion'] = '3.22.0'
 ext['javaxServletApiVersion'] ='4.0.4'
 ext['javaxServletJspJstlApiVersion'] = '1.2.7'
+ext['findbugsVersion'] = "3.0.2"
 ext['log4jVersion'] = '2.17.2'
 ext['logbackVersion'] = '1.2.3'
 ext['junitVersion'] = '4.13.2'