tests: Switch to NONE contexts in module tests

Author: jonasnick

src/modules/ecdh/tests_impl.h

@@ -26,7 +26,7 @@ int ecdh_hash_function_custom(unsigned char *output, const unsigned char *x, con
 
 void test_ecdh_api(void) {
     /* Setup context that just counts errors */
-    secp256k1_context *tctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
+    secp256k1_context *tctx = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
     secp256k1_pubkey point;
     unsigned char res[32];
     unsigned char s_one[32] = { 0 };