Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- `config/webpack/shared.js`:
  Upstream has changed how Tesseract.js gets included and dropped a dependency.
  The conflict is caused by glitch-soc having different code due to its
  theming system.
  Ported upstream changes.
- `lib/mastodon/version.rb`:
  Upstream refactor/code style change in a place we replaced upstream's
  repo URL with ours.
  Ported upstram changes, keeping our repo URL.
- `yarn.lock`:
  Upstream dropped dependencies, one of which was textually too close to
  a glitch-soc-specific dependency. Not a real conflict.

app/lib/activitypub/linked_data_signature.rb

@@ -27,7 +27,7 @@ class ActivityPub::LinkedDataSignature
     document_hash  = hash(@json.without('signature'))
     to_be_verified = options_hash + document_hash
 
-    if creator.keypair.public_key.verify(OpenSSL::Digest::SHA256.new, Base64.decode64(signature), to_be_verified)
+    if creator.keypair.public_key.verify(OpenSSL::Digest.new('SHA256'), Base64.decode64(signature), to_be_verified)
       creator
     end
   end
@@ -44,7 +44,7 @@ class ActivityPub::LinkedDataSignature
     to_be_signed  = options_hash + document_hash
     keypair       = sign_with.present? ? OpenSSL::PKey::RSA.new(sign_with) : creator.keypair
 
-    signature = Base64.strict_encode64(keypair.sign(OpenSSL::Digest::SHA256.new, to_be_signed))
+    signature = Base64.strict_encode64(keypair.sign(OpenSSL::Digest.new('SHA256'), to_be_signed))
 
     @json.merge('signature' => options.merge('signatureValue' => signature))
   end