remove CACHE_VERSION from service-worker.js (#2342)

use server_startup_time as the version
(the same trick we use for static files)

lnbits/static/js/service-worker.js

@@ -1,87 +0,0 @@
-// update cache version every time there is a new deployment
-// so the service worker reinitializes the cache
-const CACHE_VERSION = 123
-const CURRENT_CACHE = `lnbits-${CACHE_VERSION}-`
-
-const getApiKey = request => {
-  let api_key = request.headers.get('X-Api-Key')
-  if (!api_key || api_key == 'undefined') {
-    api_key = 'no_api_key'
-  }
-  return api_key
-}
-
-// on activation we clean up the previously registered service workers
-self.addEventListener('activate', evt =>
-  evt.waitUntil(
-    caches.keys().then(cacheNames => {
-      return Promise.all(
-        cacheNames.map(cacheName => {
-          const currentCacheVersion = cacheName.split('-').slice(-2, 2)
-          if (currentCacheVersion !== CACHE_VERSION) {
-            return caches.delete(cacheName)
-          }
-        })
-      )
-    })
-  )
-)
-
-// The fetch handler serves responses for same-origin resources from a cache.
-// If no response is found, it populates the runtime cache with the response
-// from the network before returning it to the page.
-self.addEventListener('fetch', event => {
-  if (
-    !event.request.url.startsWith(
-      self.location.origin + '/api/v1/payments/sse'
-    ) &&
-    event.request.url.startsWith(self.location.origin) &&
-    event.request.method == 'GET'
-  ) {
-    // Open the cache
-    event.respondWith(
-      caches.open(CURRENT_CACHE + getApiKey(event.request)).then(cache => {
-        // Go to the network first
-        return fetch(event.request)
-          .then(fetchedResponse => {
-            cache.put(event.request, fetchedResponse.clone())
-
-            return fetchedResponse
-          })
-          .catch(() => {
-            // If the network is unavailable, get
-            return cache.match(event.request.url)
-          })
-      })
-    )
-  }
-})
-
-// Handle and show incoming push notifications
-self.addEventListener('push', function (event) {
-  if (!(self.Notification && self.Notification.permission === 'granted')) {
-    return
-  }
-
-  let data = event.data.json()
-  const title = data.title
-  const body = data.body
-  const url = data.url
-
-  event.waitUntil(
-    self.registration.showNotification(title, {
-      body: body,
-      icon: '/favicon.ico',
-      data: {
-        url: url
-      }
-    })
-  )
-})
-
-// User can click on the notification message to open wallet
-// Installed app will open when `url_handlers` in web app manifest is supported
-self.addEventListener('notificationclick', function (event) {
-  event.notification.close()
-  event.waitUntil(clients.openWindow(event.notification.data.url))
-})