minor symfony#2371 Remove duplicate question mark ? in DSN string (alexander-schranz)

This PR was merged into the 2.x branch.

Discussion
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Remove duplicate question mark ? in DSN string

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  |no <!-- please update src/**/CHANGELOG.md files -->
| Issues        | Fix #... <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT

Looks like there was `??` accidently added.

Commits
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33bd17d Remove duplicate question mark ? in DSN string

Author: Kocal

src/Map/src/Bridge/Google/README.md

@@ -10,7 +10,7 @@ UX_MAP_DSN=google://GOOGLE_MAPS_API_KEY@default
 # With options
 UX_MAP_DSN=google://GOOGLE_MAPS_API_KEY@default?version=weekly
 UX_MAP_DSN=google://GOOGLE_MAPS_API_KEY@default?language=fr&region=FR
-UX_MAP_DSN=google://GOOGLE_MAPS_API_KEY@default??libraries[]=geometry&libraries[]=places
+UX_MAP_DSN=google://GOOGLE_MAPS_API_KEY@default?libraries[]=geometry&libraries[]=places
 ```
 
 Available options: