requirements: follow-up prev: rm protobuf upper bound

now that the keepkey pb2's are regenerated using the "new" format,
we don't need an old python3-protobuf to parse them

ref https://github.com/spesmilo/electrum/issues/7922

contrib/requirements/requirements-hw.txt

@@ -8,7 +8,7 @@ safet>=0.1.5
 
 # device plugin: keepkey
 ecdsa>=0.9
-protobuf>=3.0.0
+protobuf>=3.20
 mnemonic>=0.8
 hidapi>=0.7.99.post15
 libusb1>=1.6
@@ -29,10 +29,6 @@ bitbox02>=6.2.0
 cbor2>=5.4.6,<6.0.0
 pyserial>=3.5.0,<4.0.0
 
-# prefer older protobuf (see #7922)
-# (pulled in via e.g. keepkey and bitbox02)
-protobuf>=3.20,<4
-
 # prefer older colorama to avoid needing hatchling
 # (pulled in via trezor -> click -> colorama)
 # (pulled in via safet -> click -> colorama)

contrib/requirements/requirements.txt

@@ -1,5 +1,5 @@
 qrcode
-protobuf>=3.20,<4
+protobuf>=3.20
 qdarkstyle>=3.2
 aiorpcx>=0.22.0,<0.25
 aiohttp>=3.3.0,<4.0.0