Run psalm on PHP >= 7.1

Error message:
    PHP Fatal error:  Uncaught Psalm\Exception\ConfigException: Error
    parsing file /home/runner/work/php-curl-class/php-curl-class/ on
    line 8: Element '{https://getpsalm.org/schema/config}psalm': No
    matching global declaration available for the validation root.

Author: zachborboa

.github/workflows/ci.yml

@@ -47,4 +47,4 @@ jobs:
 
       - name: Static analysis
         run: "vendor/bin/psalm"
-        if: ${{ !matrix.future-release }}
+        if: ${{ !matrix.future-release && matrix.php >= 7.1 }}