Update u2f to 0.2, which requires OpenSSL but also might solve the problems we've had with certificates.

The rust image doesn't need installing curl or tar, so removed. Also collapsed ENV lines.

Cargo.toml

@@ -14,7 +14,7 @@ build = "build.rs"
 # Empty to keep compatibility, prefer to set USE_SYSLOG=true
 enable_syslog = []
 mysql = ["diesel/mysql", "diesel_migrations/mysql"]
-postgresql = ["diesel/postgres", "diesel_migrations/postgres", "openssl"]
+postgresql = ["diesel/postgres", "diesel_migrations/postgres"]
 sqlite = ["diesel/sqlite", "diesel_migrations/sqlite", "libsqlite3-sys"]
 
 [target."cfg(not(windows))".dependencies]
@@ -75,7 +75,7 @@ data-encoding = "2.1.2"
 jsonwebtoken = "6.0.1"
 
 # U2F library
-u2f = "0.1.6"
+u2f = "0.2.0"
 
 # Yubico Library
 yubico = { version = "0.7.1", features = ["online-tokio"], default-features = false }
@@ -107,8 +107,8 @@ soup = "0.4.1"
 regex = "1.3.3"
 data-url = "0.1.0"
 
-# Required for SSL support for PostgreSQL
-openssl = { version = "0.10.26", optional = true }
+# Used by U2F, JWT and Postgres
+openssl = "0.10.26"
 
 # URL encoding library
 percent-encoding = "2.1.0"