add use_zip

Cargo.toml

@@ -7,9 +7,10 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [features]
-# cargo b --features sequoia_openpgp
-default = [] # "sequoia_openpgp"
-sequoia_openpgp = ["sequoia-openpgp"]
+# cargo b --features use_sequoia_openpgp
+default = [] # "use_sequoia_openpgp"
+use_zip = []
+use_sequoia_openpgp = ["sequoia-openpgp"]
 
 [dependencies]
 dirs = "2.0.1"