Move converse and a rollup plugin to devDependencies

They were in the main dependencies, which is not really necessary.
Come to think of it, *no* dependencies should be necessary once
the thing is compiled, but the template which this project is
based on kept `sirv` as a main dependency, so I'm keeping it there.
I guess you could argue that sirv is necessary for runtime if
you're going to be running this application on a desktop for some
reason and need someway to serve the app to you.

package.json

@@ -14,6 +14,7 @@
     "@babel/plugin-syntax-dynamic-import": "^7.8.3",
     "@babel/plugin-transform-runtime": "^7.16.4",
     "@babel/preset-env": "^7.16.4",
+    "@converse/headless": "^9.1.1",
     "@rollup/plugin-babel": "^5.3.1",
     "@rollup/plugin-commonjs": "^17.0.0",
     "@rollup/plugin-json": "^4.1.0",
@@ -28,6 +29,7 @@
     "rollup": "^2.3.4",
     "rollup-plugin-css-only": "^3.1.0",
     "rollup-plugin-livereload": "^2.0.0",
+    "rollup-plugin-node-polyfills": "^0.2.1",
     "rollup-plugin-svelte": "^7.0.0",
     "rollup-plugin-terser": "^7.0.0",
     "svelte": "^3.0.0",
@@ -38,8 +40,6 @@
     "typescript": "^4.0.0"
   },
   "dependencies": {
-    "@converse/headless": "^9.1.1",
-    "rollup-plugin-node-polyfills": "^0.2.1",
     "sirv-cli": "^1.0.0"
   }
 }

yarn.lock

@@ -1914,7 +1914,7 @@ localforage-driver-memory@^1.0.5:
     localforage-driver-commons "^1.0.1"
     tslib "^1.6.0"
 
-localforage-getitems@conversejs/localForage-getItems#0f129c5c9bb0d23f8dbb64c9dfbb003c8cdf7285:
+"localforage-getitems@github:conversejs/localForage-getItems#0f129c5c9bb0d23f8dbb64c9dfbb003c8cdf7285":
   version "1.4.2"
   resolved "https://codeload.github.com/conversejs/localForage-getItems/tar.gz/0f129c5c9bb0d23f8dbb64c9dfbb003c8cdf7285"
   dependencies: