fix: make filter checks more strict (closes #1519)

quartz/plugins/filters/draft.ts

@@ -3,7 +3,7 @@ import { QuartzFilterPlugin } from "../types"
 export const RemoveDrafts: QuartzFilterPlugin<{}> = () => ({
   name: "RemoveDrafts",
   shouldPublish(_ctx, [_tree, vfile]) {
-    const draftFlag: boolean = vfile.data?.frontmatter?.draft || false
+    const draftFlag: boolean = vfile.data?.frontmatter?.draft === true
     return !draftFlag
   },
 })

quartz/plugins/filters/explicit.ts

@@ -3,6 +3,6 @@ import { QuartzFilterPlugin } from "../types"
 export const ExplicitPublish: QuartzFilterPlugin = () => ({
   name: "ExplicitPublish",
   shouldPublish(_ctx, [_tree, vfile]) {
-    return vfile.data?.frontmatter?.publish ?? false
+    return vfile.data?.frontmatter?.publish === true
   },
 })