Update immutable to 4.3.8 and enable skipLibCheck

Bump immutable from 4.0.0-rc.12 to the stable 4.3.8 release (top of the 4.x line; stays within the <5.0.0 peer ranges required by @nteract/* and redux-immutable).

immutable 4.3.8 tightened RecordOf<TProps extends Object> to extends object. The third-party @nteract/myths types (pulled in via @nteract/core) pass an unconstrained STATE to RecordOf<STATE>, which tsc rejects. Enable skipLibCheck (standard TS fix) to skip type-checking of node_modules .d.ts files; no effect on emit or our own source.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

package-lock.json

@@ -60,7 +60,7 @@
         "i18next-resources-to-backend": "1.2.1",
         "iframe-resizer-react": "1.1.0",
         "immer": "9.0.6",
-        "immutable": "4.0.0-rc.12",
+        "immutable": "4.3.8",
         "is-ci": "2.0.0",
         "jquery": "3.7.1",
         "jquery-typeahead": "2.11.1",
@@ -14508,6 +14508,7 @@
       "version": "2.3.2",
       "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.2.tgz",
       "integrity": "sha512-xiqMQR4xAeHTuB9uWm+fFRcIOgKBMiOBP+eXiyT7jsgVCq1bkVygt00oASowB7EdtpOHaaPgKt812P9ab+DDKA==",
+      "dev": true,
       "hasInstallScript": true,
       "optional": true,
       "os": [
@@ -15664,7 +15665,9 @@
       }
     },
     "node_modules/immutable": {
-      "version": "4.0.0-rc.12",
+      "version": "4.3.8",
+      "resolved": "https://registry.npmjs.org/immutable/-/immutable-4.3.8.tgz",
+      "integrity": "sha512-d/Ld9aLbKpNwyl0KiM2CT1WYvkitQ1TSvmRtkcV8FKStiDoA7Slzgjmb/1G2yhKM1p0XeNOieaTbFZmU1d3Xuw==",
       "license": "MIT"
     },
     "node_modules/import-fresh": {