fix(maven): change maven link

AppVeyor CI used a broken link of maven. We updated it
with the correct one.

Ref: yegor256#1111

appveyor.yml

@@ -14,7 +14,7 @@ install:
   - ps: |
       Add-Type -AssemblyName System.IO.Compression.FileSystem
       if (!(Test-Path -Path "C:\maven" )) {
-        (new-object System.Net.WebClient).DownloadFile('http://www.us.apache.org/dist/maven/maven-3/3.2.5/binaries/apache-maven-3.2.5-bin.zip', 'C:\maven-bin.zip')
+        (new-object System.Net.WebClient).DownloadFile('https://dlcdn.apache.org/dist/maven/maven-3/3.2.5/binaries/apache-maven-3.2.5-bin.zip', 'C:\maven-bin.zip')
         [System.IO.Compression.ZipFile]::ExtractToDirectory("C:\maven-bin.zip", "C:\maven")
       }
   - cmd: SET PATH=C:\maven\apache-maven-3.2.5\bin;%JAVA_HOME%\bin;%PATH:C:\Ruby193\bin;=%