Update LICENSE to 2021

LICENSE

@@ -8,7 +8,7 @@ disclaimer as stated in the license.
 You will require a commercial PSPDFKit License to run these examples
 in non-demo mode. Please refer to sales@pspdfkit.com for details.
 
-Copyright (c) 2010-2020, PSPDFKit GmbH.
+Copyright (c) 2010-2021, PSPDFKit GmbH.
 All rights reserved.
 
 Redistribution and use in source or binary forms,
@@ -40,4 +40,4 @@ LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.