minor symfony#36934 [travis] display deprecations in nightly jobs (nicolas-grekas)

This PR was merged into the 3.4 branch.

Discussion
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[travis] display deprecations in nightly jobs

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

Commits
-------

83a34a8 [travis] display deprecations in nightly jobs

Author: nicolas-grekas

.travis.yml

@@ -280,7 +280,7 @@ install:
       # Set composer's platform to php 7.4 if we're on php 8.
       if [[ $PHP = nightly ]]; then
           composer config platform.php 7.4.99
-          export SYMFONY_DEPRECATIONS_HELPER=weak
+          export SYMFONY_DEPRECATIONS_HELPER=max[total]=999
       fi
 
     - |