[flex/2.4] Add missing .env.dev file

[nicolas-grekas]

Q	A
License	MIT
Doc issue/PR	-

Otherwise flex cannot populate it with APP_SECRET

[github-actions]

Thanks for the PR 😍

How to test these changes in your application

1. Define the SYMFONY_ENDPOINT environment variable:

   # On Unix-like (BSD, Linux and macOS)
   export SYMFONY_ENDPOINT=https://raw.githubusercontent.com/symfony/recipes/flex/pull-1367/index.json
   # On Windows
   SET SYMFONY_ENDPOINT=https://raw.githubusercontent.com/symfony/recipes/flex/pull-1367/index.json

2. Install the package(s) related to this recipe:

   composer req symfony/flex
   composer req 'symfony/flex:^2.4'

3. Don't forget to unset the SYMFONY_ENDPOINT environment variable when done:

   # On Unix-like (BSD, Linux and macOS)
   unset SYMFONY_ENDPOINT
   # On Windows
   SET SYMFONY_ENDPOINT=

Diff between recipe versions

In order to help with the review stage, I'm in charge of computing the diff between the various versions of patched recipes.
I'm going keep this comment up to date with any updates of the attached patch.

symfony/flex

1.0 vs 2.4

diff --git a/symfony/flex/2.4/.env.dev b/symfony/flex/2.4/.env.dev
new file mode 100644
index 0000000..e69de29
diff --git a/symfony/flex/1.0/manifest.json b/symfony/flex/2.4/manifest.json
index 56f64a6..008fd44 100644
--- a/symfony/flex/1.0/manifest.json
+++ b/symfony/flex/2.4/manifest.json
@@ -1,5 +1,6 @@
 {
     "copy-from-recipe": {
-        ".env": ".env"
+        ".env": ".env",
+        ".env.dev": ".env.dev"
     }
 }