initial esm conversion

Signed-off-by: Brian DeHamer <[email protected]>

package.json

@@ -4,6 +4,7 @@
   "version": "3.2.0",
   "author": "",
   "private": true,
+  "type": "module",
   "homepage": "https://github.com/actions/attest",
   "repository": {
     "type": "git",
@@ -56,7 +57,13 @@
       "/dist/"
     ],
     "transform": {
-      "^.+\\.ts$": "ts-jest"
+      "^.+\\.ts$": ["ts-jest", {
+        "useESM": false,
+        "tsconfig": {
+          "module": "CommonJS",
+          "moduleResolution": "Node"
+        }
+      }]
     },
     "coverageReporters": [
       "json-summary",