Use sequoia-policy-config to configure the StandardPolicy.

- This allows users to tweak the StandardPolicy used by Sequoia to
    evaluate cryptographic artifacts.  For example, on Fedora it will
    adhere to the system-wide cryptographic policy for Sequoia.

  - Fixes #128.

Cargo.lock

@@ -2977,6 +2977,7 @@ dependencies = [
  "sequoia-cert-store",
  "sequoia-net",
  "sequoia-openpgp",
+ "sequoia-policy-config",
  "sequoia-wot",
  "serde",
  "serde_json",

Cargo.toml

@@ -35,6 +35,7 @@ dot-writer = "0.1.3"
 sequoia-openpgp = { version = "1.13", default-features = false, features = ["compression-deflate"] }
 sequoia-autocrypt = { version = "0.25", default-features = false, optional = true }
 sequoia-net = { version = "0.27", default-features = false }
+sequoia-policy-config = "0.6"
 anyhow = "1.0.18"
 chrono = "0.4.10"
 # For an MSRV of 1.63: 4.0.32.

src/sq.rs

@@ -1002,7 +1002,9 @@ fn main() -> Result<()> {
             .into()
     };
 
-    let policy = &mut P::at(time);
+    let mut policy = sequoia_policy_config::ConfiguredStandardPolicy::new();
+    policy.parse_default_config()?;
+    let mut policy = policy.build();
 
     let known_notations = c.known_notation
         .iter()
@@ -1022,7 +1024,7 @@ fn main() -> Result<()> {
         force,
         output_format,
         output_version,
-        policy: policy.clone(),
+        policy,
         time,
         no_rw_cert_store: c.no_cert_store,
         cert_store_path: c.cert_store.clone(),