minor #19744 [symfony/symfony] fix typo in "provides" for psr/cache-implementation (alcohol)

This PR was merged into the 3.1 branch.

Discussion
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[symfony/symfony] fix typo in "provides" for psr/cache-implementation

| Q             | A
| ------------- | ---
| Branch?       | 3.1
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #19742
| License       | MIT

Commits
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9ec4d3a fix typo

Author: nicolas-grekas

composer.json

@@ -94,7 +94,7 @@
         "phpdocumentor/reflection-docblock": "<3.0",
         "phpdocumentor/type-resolver": "<0.2.0"
     },
-    "provides": {
+    "provide": {
         "psr/cache-implementation": "1.0"
     },
     "autoload": {