Added PGPainless ref to licences.html| #1468 (#1488)

Author: DenBond7

FlowCrypt/src/main/assets/html/license.htm

@@ -27,6 +27,11 @@ <h1>Work attributions</h1>
     <p>This app uses the following:</p>
 
     <ul>
+        <li>
+            <a href="https://github.com/pgpainless/pgpainless">pgpainless/pgpainless</a>
+            (<a href="https://github.com/pgpainless/pgpainless/blob/master/LICENSE">Apache-2.0
+            License</a>)
+        </li>
         <li>
             <a href="https://github.com/ACRA/acra">ACRA/acra</a>
             (<a href="https://github.com/acra/acra/blob/master/LICENSE">Apache-2.0 License</a>)
@@ -37,7 +42,8 @@ <h1>Work attributions</h1>
         </li>
         <li>
             <a href="https://github.com/square/retrofit">square/retrofit</a>
-            (<a href="https://github.com/square/retrofit/blob/master/LICENSE.txt">Apache-2.0 License</a>)
+            (<a href="https://github.com/square/retrofit/blob/master/LICENSE.txt">Apache-2.0
+            License</a>)
         </li>
         <li>
             <a href="https://github.com/square/okhttp">square/okhttp</a>