wine build: remove pgp.mit.edu from keyservers

sometimes slow, and does not return all the pubkeys asked for (so build fails)

contrib/build-wine/prepare-wine.sh

@@ -96,8 +96,7 @@ KEYRING_PYTHON_DEV="keyring-electrum-build-python-dev.gpg"
 for server in $(shuf -e ha.pool.sks-keyservers.net \
                         hkp://p80.pool.sks-keyservers.net:80 \
                         keyserver.ubuntu.com \
-                        hkp://keyserver.ubuntu.com:80 \
-                        pgp.mit.edu) ; do
+                        hkp://keyserver.ubuntu.com:80) ; do
     retry gpg --no-default-keyring --keyring $KEYRING_PYTHON_DEV --keyserver "$server" --recv-keys $KEYLIST_PYTHON_DEV \
     && break || : ;
 done