Remove execa dependency

package.json

@@ -43,7 +43,6 @@
     "eslint-plugin-react": "^7.1.0",
     "eslint-plugin-relay": "^1.0.0",
     "eslint-plugin-yarn-internal": "file:scripts/eslint-rules",
-    "execa": "^1.0.0",
     "flow-bin": "0.88.0",
     "is-builtin-module": "^3.0.0",
     "jest": "^23.6.0",

yarn.lock

@@ -1896,7 +1896,7 @@ cross-spawn@^5.0.1:
     shebang-command "^1.2.0"
     which "^1.2.9"
 
-cross-spawn@^6.0.0, cross-spawn@^6.0.5:
+cross-spawn@^6.0.5:
   version "6.0.5"
   resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-6.0.5.tgz#4a5ec7c64dfae22c3a14124dbacdee846d80cbc4"
   integrity sha512-eTVLrBSt7fjbDygz805pMnstIs2VTBNkRm0qxZd+M7A5XDdxVRWO5MxGBXZhjY4cqLYLdtrGqRf8mBPmzwSpWQ==
@@ -2531,19 +2531,6 @@ execa@^0.7.0:
     signal-exit "^3.0.0"
     strip-eof "^1.0.0"
 
-execa@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/execa/-/execa-1.0.0.tgz#c6236a5bb4df6d6f15e88e7f017798216749ddd8"
-  integrity sha512-adbxcyWV46qiHyvSp50TKt05tB4tK3HcmF7/nxfAdhnox83seTDbwnaqKO4sXRy7roHAIFqJP/Rw/AuEbX61LA==
-  dependencies:
-    cross-spawn "^6.0.0"
-    get-stream "^4.0.0"
-    is-stream "^1.1.0"
-    npm-run-path "^2.0.0"
-    p-finally "^1.0.0"
-    signal-exit "^3.0.0"
-    strip-eof "^1.0.0"
-
 execa@^4.0.0:
   version "4.0.3"
   resolved "https://registry.yarnpkg.com/execa/-/execa-4.0.3.tgz#0a34dabbad6d66100bd6f2c576c8669403f317f2"
@@ -2892,7 +2879,7 @@ get-stream@^3.0.0:
   resolved "https://registry.yarnpkg.com/get-stream/-/get-stream-3.0.0.tgz#8e943d1358dc37555054ecbe2edb05aa174ede14"
   integrity sha1-jpQ9E1jcN1VQVOy+LtsFqhdO3hQ=
 
-get-stream@^4.0.0, get-stream@^4.1.0:
+get-stream@^4.1.0:
   version "4.1.0"
   resolved "https://registry.yarnpkg.com/get-stream/-/get-stream-4.1.0.tgz#c1b255575f3dc21d59bfc79cd3d2b46b1c3a54b5"
   integrity sha512-GMat4EJ5161kIy2HevLlr4luNjBgvmj413KaQA7jt4V8B4RDsfpHk7WQ9GVqfYyyx8OS/L66Kox+rJRNklLK7w==