Remove no longer used files from asset validation (#13372)

Also removed temporary sha value needed for initial 3.0.0-beta.1

script/prepare-release.js

@@ -75,7 +75,7 @@ async function getReleaseNotes (currentBranch) {
   let githubOpts = {
     owner: 'electron',
     repo: 'electron',
-    base: `2a97e48465a3af9e5448a8d06c1d65d16c516e8f`,
+    base: `v${pkg.version}`,
     head: currentBranch
   }
   let releaseNotes

script/release.js

@@ -90,8 +90,6 @@ function assetsForVersion (version, validatingRelease) {
     `electron-${version}-darwin-x64-dsym.zip`,
     `electron-${version}-darwin-x64-symbols.zip`,
     `electron-${version}-darwin-x64.zip`,
-    `electron-${version}-linux-arm-symbols.zip`,
-    `electron-${version}-linux-arm.zip`,
     `electron-${version}-linux-arm64-symbols.zip`,
     `electron-${version}-linux-arm64.zip`,
     `electron-${version}-linux-armv7l-symbols.zip`,
@@ -113,7 +111,6 @@ function assetsForVersion (version, validatingRelease) {
     `electron-api.json`,
     `electron.d.ts`,
     `ffmpeg-${version}-darwin-x64.zip`,
-    `ffmpeg-${version}-linux-arm.zip`,
     `ffmpeg-${version}-linux-arm64.zip`,
     `ffmpeg-${version}-linux-armv7l.zip`,
     `ffmpeg-${version}-linux-ia32.zip`,