Switched to Apache License

Updates this release:

• Merged in "Added insert() API to cards.rs" PR
• Updated GitHub Actions
• Switched to Apache 2.0 License
• Fixed badges
• Updated Fluent Templates to version 0.7.1.
• Updated RSTest to version 0.16.0.
• Updated minimum Rust version to 1.63.

Note: Was unable to update Fluent Templates to version 0.8.0. Generates this error:

error[E0308]: mismatched types
  --> src/fluent/named.rs:29:9
   |
27 |     fn fluent_value(&self, key_section: &str, lid: &LanguageIdentifier) -> std::string::String {
   |                                                                            ------------------- expected `std::string::String` because of return type
28 |         let id = format!("{}-{}", self.name(), key_section);
29 |         LOCALES.lookup(lid, id.as_str())
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected struct `std::string::String`, found enum `Option`
   |
   = note: expected struct `std::string::String`
                found enum `Option<std::string::String>`