Merge #1586: fix: remove duplicate 'the' from header file comment

9b0f37b fix: remove duplicate 'the' from header file comment (Epic Curious)

Pull request description:

  Replaces:
  ` * Changes w.r.t. the the paper:`

  With:
  ` * Changes w.r.t. the paper:`

  in the `include/secp256k1_ellswift.h` header file.

ACKs for top commit:
  real-or-random:
    ACK 9b0f37b

Tree-SHA512: a0ac153d91f0d27959d626ede116e5322fcab7e32d8e6e81bd570cbb3eae55054ab6d0310bdf963bf4fddf9792c79fad61bc90a69bc24ab5234f29e4a2763ef3

include/secp256k1_ellswift.h

@@ -35,7 +35,7 @@ extern "C" {
  *
  * If the Y coordinate is relevant, it is given the same parity as t.
  *
- * Changes w.r.t. the the paper:
+ * Changes w.r.t. the paper:
  * - The u=0, t=0, and u^3+t^2+7=0 conditions result in decoding to the point
  *   at infinity in the paper. Here they are remapped to finite points.
  * - The paper uses an additional encoding bit for the parity of y. Here the