add inputs/outputs to npm_run_build

Fixes the up-to-date check for npm_run_build.

pdb-js/build.gradle

@@ -45,6 +45,14 @@ sourceSets {
     }
 }
 
+npm_run_build.inputs.dir("src").withPropertyName("sourceFiles")
+npm_run_build.inputs.files(fileTree("src/templates") {
+  include "*.json"
+  include "*.js"
+  include "browserslist"
+})
+npm_run_build.outputs.dir("build/generated").withPropertyName("outputFiles")
+
 
 jar.dependsOn 'npm_run_build'