Update dependencies

Pin the ESLint dev dependency to ensure we test the minimal required
version.

Remove unused codecov dependency.

package.json

@@ -32,19 +32,18 @@
 	"dependencies": {
 		"deep-strict-equal": "^0.2.0",
 		"enhance-visitors": "^1.0.0",
-		"espree": "^6.0.0",
-		"espurify": "^2.0.0",
-		"import-modules": "^1.1.0",
+		"espree": "^6.1.2",
+		"espurify": "^2.0.1",
+		"import-modules": "^2.0.0",
 		"pkg-dir": "^4.2.0",
 		"resolve-from": "^5.0.0"
 	},
 	"devDependencies": {
 		"ava": "^2.3.0",
 		"babel-eslint": "^10.0.2",
 		"chalk": "^2.4.2",
-		"codecov": "^3.5.0",
 		"del": "^5.0.0",
-		"eslint": "^6.2.0",
+		"eslint": "6.2.0",
 		"eslint-ava-rule-tester": "^3.0.0",
 		"eslint-plugin-eslint-plugin": "2.1.0",
 		"execa": "^2.0.4",
@@ -57,7 +56,7 @@
 		"xo": "^0.24.0"
 	},
 	"peerDependencies": {
-		"eslint": ">=6.2.0"
+		"eslint": "^6.2.0"
 	},
 	"ava": {
 		"files": [