fix(build): update cross-env to v5.2.0

The v5.2.0 includes (amongst other things) a fix for incorrectly reported
exit codes of child processes, which can prevent build build failures from
correctly halting a build, resulting in incomplete or invalid builds.

See kentcdodds/cross-env#150 (comment)

package.json

@@ -157,7 +157,7 @@
     "browserslist": "^2.11.0",
     "chalk": "^2.0.1",
     "concurrently": "^3.5.1",
-    "cross-env": "^5.0.0",
+    "cross-env": "^5.2.0",
     "cross-spawn": "^5.1.0",
     "css-loader": "^0.28.3",
     "electron-builder": "^20.15.0",

yarn.lock

@@ -2686,11 +2686,11 @@ create-react-class@^15.6.0:
     loose-envify "^1.3.1"
     object-assign "^4.1.1"
 
-cross-env@^5.0.0:
-  version "5.0.1"
-  resolved "https://registry.yarnpkg.com/cross-env/-/cross-env-5.0.1.tgz#ff4e72ea43b47da2486b43a7f2043b2609e44913"
+cross-env@^5.2.0:
+  version "5.2.0"
+  resolved "https://registry.yarnpkg.com/cross-env/-/cross-env-5.2.0.tgz#6ecd4c015d5773e614039ee529076669b9d126f2"
   dependencies:
-    cross-spawn "^5.1.0"
+    cross-spawn "^6.0.5"
     is-windows "^1.0.0"
 
 cross-spawn@^3.0.0:
@@ -2708,6 +2708,16 @@ cross-spawn@^5.0.1, cross-spawn@^5.1.0:
     shebang-command "^1.2.0"
     which "^1.2.9"
 
+cross-spawn@^6.0.5:
+  version "6.0.5"
+  resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-6.0.5.tgz#4a5ec7c64dfae22c3a14124dbacdee846d80cbc4"
+  dependencies:
+    nice-try "^1.0.4"
+    path-key "^2.0.1"
+    semver "^5.5.0"
+    shebang-command "^1.2.0"
+    which "^1.2.9"
+
 cross-unzip@0.0.2:
   version "0.0.2"
   resolved "https://registry.yarnpkg.com/cross-unzip/-/cross-unzip-0.0.2.tgz#5183bc47a09559befcf98cc4657964999359372f"
@@ -6805,6 +6815,10 @@ negotiator@0.6.1:
   version "0.6.1"
   resolved "https://registry.yarnpkg.com/negotiator/-/negotiator-0.6.1.tgz#2b327184e8992101177b28563fb5e7102acd0ca9"
 
+nice-try@^1.0.4:
+  version "1.0.4"
+  resolved "https://registry.yarnpkg.com/nice-try/-/nice-try-1.0.4.tgz#d93962f6c52f2c1558c0fbda6d512819f1efe1c4"
+
 no-case@^2.2.0:
   version "2.3.1"
   resolved "https://registry.yarnpkg.com/no-case/-/no-case-2.3.1.tgz#7aeba1c73a52184265554b7dc03baf720df80081"
@@ -7376,7 +7390,7 @@ path-is-inside@^1.0.1, path-is-inside@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/path-is-inside/-/path-is-inside-1.0.2.tgz#365417dede44430d1c11af61027facf074bdfc53"
 
-path-key@^2.0.0:
+path-key@^2.0.0, path-key@^2.0.1:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/path-key/-/path-key-2.0.1.tgz#411cadb574c5a140d3a4b1910d40d80cc9f40b40"