Update eslint plugin & fix silly indenting

As per https://github.com/matrix-org/eslint-plugin-matrix-org/pull/15
this caused a bunch of silly indenting to creep in, so this fixes it
back to the previous style.

test/notifications/ContentRules-test.js

@@ -56,7 +56,7 @@ describe("ContentRules", function() {
     describe("parseContentRules", function() {
         it("should handle there being no keyword rules", function() {
             const rules = { 'global': { 'content': [
-                    USERNAME_RULE,
+                USERNAME_RULE,
             ] } };
             const parsed = ContentRules.parseContentRules(rules);
             expect(parsed.rules).toEqual([]);