chore: bump version to 2.1

Author: dufkan

CITATION.cff

@@ -8,7 +8,7 @@ authors:
 - family-names: "Dufka"
  given-names: "Antonin"
 title: "JCMathLib"
-version: 2.0
+version: 2.1
 url: "https://github.com/OpenCryptoProject/JCMathLib"
 preferred-citation:
  type: conference-paper

applet/build.gradle

@@ -1,5 +1,5 @@
 group 'test-applet'
-version '2.0'
+version '2.1'
 
 // Buildscript configuration for the javacard-gradle plugin.
 // Do not modify this particular block. Dependencies for the project are lower.