make cel-rust pass conformance tests

Author: Flaque

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "cel-spec"]
+	path = cel-spec
+	url = https://github.com/google/cel-spec.git

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-members = ["cel", "example", "fuzz"]
+members = ["cel", "example", "fuzz", "conformance"]
 resolver = "2"
 
 [profile.bench]

README.md

@@ -7,6 +7,8 @@ for simplicity, speed, safety, and
 portability. CEL's C-like syntax looks nearly identical to equivalent expressions in C++, Go, Java, and TypeScript. CEL
 is ideal for lightweight expression evaluation when a fully sandboxed scripting language is too resource intensive.
 
+It passes all conformance tests. 
+
 ```java
 // Check whether a resource name starts with a group name.
 resource.name.startsWith("/groups/" + auth.claims.group)

cel-spec

@@ -14,10 +14,12 @@ antlr4rust = "0.5.2"
 lazy_static = "1.5.0"
 nom = "7.1.3"
 chrono = { version = "0.4", default-features = false, features = ["alloc", "serde"], optional = true }
+chrono-tz = { version = "0.8", optional = true }
 regex = { version = "1.10.5", optional = true }
 serde = "1.0"
 serde_json = { version = "1.0", optional = true }
 base64 = { version = "0.22.1", optional = true }
+prost = { version = "0.12", optional = true }
 bytes = { version = "1", optional = true }
 
 thiserror = "1.0"
@@ -37,5 +39,6 @@ default = ["regex", "chrono"]
 bytes = ["dep:bytes"]
 json = ["dep:serde_json", "dep:base64"]
 regex = ["dep:regex"]
-chrono = ["dep:chrono"]
+chrono = ["dep:chrono", "dep:chrono-tz"]
+proto = ["dep:prost"]
 dhat-heap = [ ] # if you are doing heap profiling