upgrade @observablehq/stdlib to 5.8.8 (#372)

* https://github.com/observablehq/stdlib/releases/tag/v5.8.8
* https://github.com/observablehq/inputs/releases/tag/v0.11.0
* https://github.com/observablehq/plot/releases/tag/v0.6.16

Author: Fil

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@observablehq/runtime",
-  "version": "5.9.8",
+  "version": "5.9.9",
   "author": {
     "name": "Observable, Inc.",
     "url": "https://observablehq.com"

yarn.lock

@@ -126,9 +126,9 @@
     isoformat "^0.2.0"
 
 "@observablehq/stdlib@^5.0.0":
-  version "5.8.7"
-  resolved "https://registry.yarnpkg.com/@observablehq/stdlib/-/stdlib-5.8.7.tgz#504a3be1327bf07f8e91b55f64b47479ca9615f4"
-  integrity sha512-XU/lwtjZBAXTZstnBULrpr0v7jbTZqfZPLNeq54H3E9IGFQyjiwFSXDNUNv1PtS6Scts0x6toj47CB4075EmeA==
+  version "5.8.8"
+  resolved "https://registry.yarnpkg.com/@observablehq/stdlib/-/stdlib-5.8.8.tgz#a5c7f6d75f6b5e1b62cbbca467ce929347cf231f"
+  integrity sha512-XxVfXX4N+8QYqg308+KT2cpXcsiL6yFphrYNOyCNReqezeoK0Zd9xOdSvo/0NX8NJ8HypIZdTQNwPeOvQWOm2Q==
   dependencies:
     d3-array "^3.2.0"
     d3-dsv "^3.0.1"