Revert to monolog 2.x

Reverts to `monolog/monolog` 2.x as 3.x is incompatible with `maxbanton/cwh` causing a fatal on AWS

- Addresses #1074

(cherry picked from commit 779badf)

Author: mikelittle

composer.json

@@ -38,7 +38,7 @@
 		"humanmade/batcache": "~1.5.2",
 		"humanmade/ludicrousdb": "~5.0.7",
 		"humanmade/aws-ses-wp-mail": "~1.3.1",
-		"monolog/monolog": "^3.9",
+		"monolog/monolog": "^2.9",
 		"maxbanton/cwh": "^2.0"
 	},
 	"extra": {