Downgraded fs-extra version to 6.x to fix a fs.copy related issue.

fs-extra brought in a breaking change here:
jprichardson/node-fs-extra#582

where it breaks ember-try when copying node_modules/ and there's
a symlink in it. The bug would either prevent ember-try from
running or cleaning up after try-each.

@co-authored-by hjdivad

Author: Larry Yu

package.json

@@ -35,7 +35,7 @@
     "debug": "^4.3.2",
     "ember-try-config": "^4.0.0",
     "execa": "^4.1.0",
-    "fs-extra": "^9.0.1",
+    "fs-extra": "^6.0.1",
     "resolve": "^1.20.0",
     "rimraf": "^3.0.2",
     "walk-sync": "^2.2.0"

yarn.lock

@@ -3460,6 +3460,15 @@ fs-extra@^5.0.0:
     jsonfile "^4.0.0"
     universalify "^0.1.0"
 
+fs-extra@^6.0.1:
+  version "6.0.1"
+  resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-6.0.1.tgz#8abc128f7946e310135ddc93b98bddb410e7a34b"
+  integrity sha512-GnyIkKhhzXZUWFCaJzvyDLEEgDkPfb4/TPvJCJVuS8MWZgoSsErf++QpiAlDnKFcqhRlm+tIOcencCjyJE6ZCA==
+  dependencies:
+    graceful-fs "^4.1.2"
+    jsonfile "^4.0.0"
+    universalify "^0.1.0"
+
 fs-extra@^8.0.1, fs-extra@^8.1.0:
   version "8.1.0"
   resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-8.1.0.tgz#49d43c45a88cd9677668cb7be1b46efdb8d2e1c0"
@@ -3469,7 +3478,7 @@ fs-extra@^8.0.1, fs-extra@^8.1.0:
     jsonfile "^4.0.0"
     universalify "^0.1.0"
 
-fs-extra@^9.0.0, fs-extra@^9.0.1:
+fs-extra@^9.0.0:
   version "9.0.1"
   resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-9.0.1.tgz#910da0062437ba4c39fedd863f1675ccfefcb9fc"
   integrity sha512-h2iAoN838FqAFJY2/qVpzFXy+EBxfVE220PalAqQLDVsFOHLJrZvut5puAbCdNv6WJk+B8ihI+k0c7JK5erwqQ==