fix: --open throwing error (#105)

Moved `execa` to dependencies rather than devDependencies.

package.json

@@ -65,6 +65,7 @@
     "debug": "^4.1.1",
     "es-module-lexer": "^0.3.18",
     "esbuild": "^0.2.6",
+    "execa": "^4.0.1",
     "fs-extra": "^9.0.0",
     "hash-sum": "^2.0.0",
     "koa": "^2.11.0",
@@ -99,7 +100,6 @@
     "@types/serve-handler": "^6.1.0",
     "@types/ws": "^7.2.4",
     "conventional-changelog-cli": "^2.0.31",
-    "execa": "^4.0.0",
     "jest": "^25.4.0",
     "lint-staged": "^10.1.6",
     "npm-run-all": "^4.1.5",

yarn.lock

@@ -2633,6 +2633,21 @@ execa@^4.0.0:
     signal-exit "^3.0.2"
     strip-final-newline "^2.0.0"
 
+execa@^4.0.1:
+  version "4.0.1"
+  resolved "https://registry.yarnpkg.com/execa/-/execa-4.0.1.tgz#988488781f1f0238cd156f7aaede11c3e853b4c1"
+  integrity sha512-SCjM/zlBdOK8Q5TIjOn6iEHZaPHFsMoTxXQ2nvUvtPnuohz3H2dIozSg+etNR98dGoYUp2ENSKLL/XaMmbxVgw==
+  dependencies:
+    cross-spawn "^7.0.0"
+    get-stream "^5.0.0"
+    human-signals "^1.1.1"
+    is-stream "^2.0.0"
+    merge-stream "^2.0.0"
+    npm-run-path "^4.0.0"
+    onetime "^5.1.0"
+    signal-exit "^3.0.2"
+    strip-final-newline "^2.0.0"
+
 exit@^0.1.2:
   version "0.1.2"
   resolved "https://registry.yarnpkg.com/exit/-/exit-0.1.2.tgz#0632638f8d877cc82107d30a0fff1a17cba1cd0c"