build: replace "std" flag dep in "miniscript" flag

Also added miniscript flag to default. The miniscript flag
is retained so as to not be coupled with "download" or "std".

Author: 110CodingP

crates/testenv/Cargo.toml

@@ -25,8 +25,8 @@ tempfile = "3.20.0"
 bdk_testenv = { path = "." }
 
 [features]
-default = ["std", "download"]
-miniscript = ["std", "bdk_chain/miniscript"]
+default = ["std" , "download", "miniscript"]
+miniscript = ["bdk_chain/default"]
 download = ["electrsd/bitcoind_25_0", "electrsd/esplora_a33e97e1"]
 std = ["bdk_chain/std"]
 serde = ["bdk_chain/serde"]