Fix documentation of used digest and signature algorithm

SHA-256 is used since 2019.
This amends c9f8893000.

Pick-to: 6.7 6.6 6.5
Change-Id: I005aa3414e4606045c8c3b01d71547efcf4122ba
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>
Reviewed-by:  Alexey Edelev <alexey.edelev@qt.io>

src/tools/androiddeployqt/main.cpp

@@ -609,9 +609,9 @@ Optional arguments:
            from keystore password.)
          --sigfile <file>: Name of .SF/.DSA file.
          --digestalg <name>: Name of digest algorithm. Default is
-           "SHA1".
+           "SHA-256".
          --sigalg <name>: Name of signature algorithm. Default is
-           "SHA1withRSA".
+           "SHA256withRSA".
          --tsa <url>: Location of the Time Stamping Authority.
          --tsacert <alias>: Public key certificate for TSA.
          --internalsf: Include the .SF file inside the signature block.