Excavator: Update open-source publishing plugins (#1558)

Author: svc-excavator-bot

build.gradle

@@ -10,7 +10,7 @@ buildscript {
         classpath 'com.palantir.baseline-error-prone:gradle-baseline-error-prone:0.7.0'
         classpath 'com.palantir.baseline:gradle-baseline-java:6.80.0'
         classpath 'com.palantir.gradle.consistentversions:gradle-consistent-versions:3.8.0'
-        classpath 'com.palantir.gradle.externalpublish:gradle-external-publish-plugin:1.29.0'
+        classpath 'com.palantir.gradle.externalpublish:gradle-external-publish-plugin:1.31.0'
         classpath 'com.palantir.gradle.failure-reports:gradle-failure-reports:1.18.0'
         classpath 'com.palantir.gradle.gitversion:gradle-git-version:4.3.0'
         classpath 'com.palantir.gradle.guide:gradle-guide:1.27.0'