Replace deprecated SHA1 functions

[icraggs]

Warnings:

/home/icraggs/git/paho.mqtt.c/src/WebSocket.c:1324:17: warning: ‘SHA1_Init’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
 1324 |                 SHA1_Init( &ctx );

/home/icraggs/git/paho.mqtt.c/src/WebSocket.c:1325:17: warning: ‘SHA1_Update’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
 1325 |                 SHA1_Update( &ctx, ws_key, strlen(ws_key));

/home/icraggs/git/paho.mqtt.c/src/WebSocket.c:1326:17: warning: ‘SHA1_Final’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
 1326 |                 SHA1_Final( sha_hash, &ctx );

Old code:

   SHA_CTX c;
   SHA1_Init(&c);
   SHA1_Update(&c, (const unsigned char *)str, length < 0 ? (unsigned)strlen(str) : (unsigned)length);
   SHA1_Final(&(md[0]), &c);

Replace with:

   EVP_MD_CTX *sha1_ctx = EVP_MD_CTX_new();
   EVP_DigestInit(sha1_ctx, EVP_sha1());
   EVP_DigestUpdate(sha1_ctx, (const unsigned char *)str, length < 0 ? (unsigned)strlen(str) : (unsigned)length);
   EVP_DigestFinal(sha1_ctx, md, NULL);