fix issue with conflicting EC2 permissions calling AWS STS

lib/get-aws-sts-token.js

@@ -14,13 +14,14 @@ async function getAwsAuthToken(
     if (obj) return {...obj, servedFromCache: true};
 
     /* access token not found in cache, so generate it using STS */
-    const stsClient = new STSClient({ region: awsRegion });
-    const params = {
-      accessKeyId: awsAccessKeyId,
-      secretAccessKey: awsSecretAccessKey,
-      DurationSeconds: EXPIRY
-    };
-    const command = new GetSessionTokenCommand(params);
+    const stsClient = new STSClient({
+      region: awsRegion,
+      credentials: {
+        accessKeyId: awsAccessKeyId,
+        secretAccessKey: awsSecretAccessKey,
+      }
+    });
+    const command = new GetSessionTokenCommand({DurationSeconds: EXPIRY});
     const data = await stsClient.send(command);
 
     const credentials = {