Fix typos (#19849)

Found via `codespell -q 3 -S ./yarn.lock,./CHANGELOG.md,./AUTHORS.md,./config/locales,./app/javascript/mastodon/locales -L ba,followings,keypair,medias,pattens,pixelx,rememberable,ro,te`

spec/lib/webfinger_resource_spec.rb

@@ -50,7 +50,7 @@ describe WebfingerResource do
       end
 
       it 'finds the username in a mixed case http route' do
-        resource = 'HTTp://exAMPLEe.com/users/alice'
+        resource = 'HTTp://exAMPLe.com/users/alice'
 
         result = WebfingerResource.new(resource).username
         expect(result).to eq 'alice'

spec/models/account_spec.rb

@@ -255,7 +255,7 @@ RSpec.describe Account, type: :model do
         Fabricate(:status, reblog: original_status, account: author)
       end
 
-      it 'is is true when this account has favourited it' do
+      it 'is true when this account has favourited it' do
         Fabricate(:favourite, status: original_reblog, account: subject)
 
         expect(subject.favourited?(original_status)).to eq true
@@ -267,7 +267,7 @@ RSpec.describe Account, type: :model do
     end
 
     context 'when the status is an original status' do
-      it 'is is true when this account has favourited it' do
+      it 'is true when this account has favourited it' do
         Fabricate(:favourite, status: original_status, account: subject)
 
         expect(subject.favourited?(original_status)).to eq true