Update Spring Boot to 2.6.1

Author: ynojima

build.gradle

@@ -199,7 +199,7 @@ configure(allJavaProjects) {
 
     def webauthn4jVersion = '0.18.0.RELEASE'
     def springSecurityVersion = '5.6.0'
-    def springBootVersion = '2.3.1.RELEASE'
+    def springBootVersion = '2.6.1'
     def hibernateValidatorVersion = '6.2.0.Final'
     def thymeleafVersion = '3.0.4.RELEASE'
     def modelMapperVersion = '2.4.4'

webauthn4j-spring-security-core/src/test/java/com/webauthn4j/springframework/security/options/AttestationOptionsProviderImplTest.java

@@ -138,7 +138,7 @@ public void getter_setter_test() {
         assertThat(optionsProvider.getRpId()).isEqualTo("example.com");
         optionsProvider.setRpName("example");
         assertThat(optionsProvider.getRpName()).isEqualTo("example");
-        List<PublicKeyCredentialParameters> publicKeyCredParams = Lists.emptyList();
+        List<PublicKeyCredentialParameters> publicKeyCredParams = Lists.newArrayList();
         optionsProvider.setPubKeyCredParams(publicKeyCredParams);
         assertThat(optionsProvider.getPubKeyCredParams()).isEqualTo(publicKeyCredParams);
         optionsProvider.setRegistrationTimeout(10000L);