Update dependency dev.equo.ide:solstice to v1.7.3

Author: renovate[bot]

lib-extra/build.gradle

@@ -7,7 +7,7 @@ version = rootProject.spotlessChangelog.versionNext
 apply from: rootProject.file('gradle/java-setup.gradle')
 apply from: rootProject.file('gradle/java-publish.gradle')
 
-String VER_SOLSTICE = '1.3.1'
+String VER_SOLSTICE = '1.7.3'
 dependencies {
 	api project(':lib')
 	// misc useful utilities