Add support for revoking a refresh token (#91)

According to [RFC 7009, Section
2.1](https://datatracker.ietf.org/doc/html/rfc7009#section-2.1), the
`token_type_hint` parameter for token revocation requests is optional.
Therefore, we only set the `token_type_hint` when the options.tokenType
is specified.

src/index.ts

@@ -388,16 +388,21 @@ export class OAuth2Strategy<
 	}
 
 	public revokeToken(
-		accessToken: string,
-		options: { signal?: AbortSignal } = {},
+		token: string,
+		options: {
+			signal?: AbortSignal;
+			tokenType?: "access_token" | "refresh_token";
+		} = {},
 	) {
 		if (this.options.tokenRevocationEndpoint === undefined) {
 			throw new Error("Token revocation endpoint is not set");
 		}
 
-		let context = new TokenRevocationRequestContext(accessToken);
+		let context = new TokenRevocationRequestContext(token);
 
-		context.setTokenTypeHint("access_token");
+		if (options.tokenType) {
+			context.setTokenTypeHint(options.tokenType);
+		}
 
 		if (this.options.authenticateWith === "http_basic_auth") {
 			context.authenticateWithHTTPBasicAuth(
@@ -412,7 +417,7 @@ export class OAuth2Strategy<
 		}
 
 		return sendTokenRevocationRequest(
-			this.options.tokenEndpoint.toString(),
+			this.options.tokenRevocationEndpoint.toString(),
 			context,
 			{ signal: options.signal },
 		);