requirements-hw: pin ledger-bitcoin to "<0.2.2"

ledger-bitcoin==0.2.2 added new deps we don't want to bundle. otherwise it should be ok to use.
see https://github.com/LedgerHQ/app-bitcoin-new/issues/192

contrib/requirements/requirements-hw.txt

@@ -11,8 +11,10 @@ keepkey>=6.3.1
 
 # device plugin: ledger
 # note: btchip-python only needed for "legacy" protocol and HW.1 support
+# note: ledger-bitcoin==0.2.2 added new deps we don't want to bundle. otherwise it should be ok to use.
+        see https://github.com/LedgerHQ/app-bitcoin-new/issues/192
 btchip-python>=0.1.32
-ledger-bitcoin>=0.2.0,<0.3.0
+ledger-bitcoin>=0.2.0,<0.2.2
 hidapi
 
 # device plugin: coldcard