Update block explorer URL for btc.com (#5438)

* update block explorer URL for btc.com

electrum/util.py

@@ -660,8 +660,8 @@ mainnet_block_explorers = {
                         {'tx': 'tx/', 'addr': 'address/'}),
     'Bitaps.com': ('https://btc.bitaps.com/',
                         {'tx': '', 'addr': ''}),
-    'BTC.com': ('https://chain.btc.com/',
+    'BTC.com': ('https://btc.com/',
-                        {'tx': 'tx/', 'addr': 'address/'}),
+                        {'tx': '', 'addr': ''}),
     'Chain.so': ('https://www.chain.so/',
                         {'tx': 'tx/BTC/', 'addr': 'address/BTC/'}),
     'Insight.is': ('https://insight.bitpay.com/',
@@ -691,8 +691,6 @@ testnet_block_explorers = {
                        {'tx': 'tx/', 'addr': 'address/'}),
     'Blockstream.info': ('https://blockstream.info/testnet/',
                         {'tx': 'tx/', 'addr': 'address/'}),
-    'BTC.com': ('https://tchain.btc.com/',
-                       {'tx': '', 'addr': ''}),
     'smartbit.com.au': ('https://testnet.smartbit.com.au/',
                        {'tx': 'tx/', 'addr': 'address/'}),
     'system default': ('blockchain://000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943/',