Revert "Add automatic notification about js API change on install"

`npm` since `v7` doesn't display the output of lifecycle scripts (see
https://docs.npmjs.com/cli/v9/using-npm/logging?v=true#foreground-scripts),
so the automatic notification no longer works. The note in README will
have to suffice.

This reverts commit 1be1580.

build.sbt

@@ -249,11 +249,9 @@ lazy val buildNpmPackageTask = Def.task {
   val licenseFile = new File("js/npm/LICENSE")
   val readMeFile = new File("js/npm/README.md")
   val packageJsonFile = new File("js/npm/package.json")
-  val warnFile = new File("js/npm/warn-about-constructor-bc-break.js")
 
   Files.copy(new File("LICENSE").toPath, licenseFile.toPath)
   Files.copy(new File("js/README.md").toPath, readMeFile.toPath)
-  Files.copy(new File("js/warn-about-constructor-bc-break.js").toPath, warnFile.toPath)
 
   val packageJsonTmpl = IO.read(new File("js/package.json"), UTF8)
   val packageJsonContents = packageJsonTmpl.replaceFirst(
@@ -266,7 +264,6 @@ lazy val buildNpmPackageTask = Def.task {
   Seq(
     licenseFile,
     readMeFile,
-    packageJsonFile,
-    warnFile,
+    packageJsonFile
   )
 }

js/package.json

@@ -33,7 +33,6 @@
     "url": "git+https://github.com/kaitai-io/kaitai_struct_compiler.git"
   },
   "scripts": {
-    "postinstall": "node warn-about-constructor-bc-break.js",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "version": "OVERRIDDEN BY /build.sbt"