Switch to release version of flatbuffers-gwt

Author: niloc132

buildSrc/src/main/groovy/io.deephaven.repository-conventions.gradle

@@ -1,8 +1,5 @@
 repositories {
     mavenCentral()
-    maven {
-        url 'https://oss.sonatype.org/content/repositories/snapshots/'
-    }
     maven {
         url 'https://jitpack.io'
         content {

gradle/libs.versions.toml

@@ -77,7 +77,7 @@ trove = "3.0.3"
 undercouch = "2.15.1"
 univocity = "2.6.0"
 vertispan-nio = "1.0-alpha-2"
-vertispan-flatbuffers-gwt = "1.12.0-1-SNAPSHOT"
+vertispan-flatbuffers-gwt = "1.12.0-1"
 vertispan-ts-defs = "1.0.0-RC4"
 
 # test versions