Fix: EZP-23531 - ezpublish-legacy composer.json pointing to ~5.3 instead of dev-master

#### EZP-23531 - ezpublish-legacy composer.json pointing to ~5.3 instead of dev-master

The https://github.com/ezsystems/ezpublish-legacy/blob/master/composer.json file points ~5.3 on the legacy ezsystems extensions when it should be poiting to dev-master

```
        "ezsystems/ezautosave-ls": "~5.3",
        "ezsystems/ezdemo-ls-extension": "~5.3",
        "ezsystems/ezflow-ls-extension": "~5.3",
        "ezsystems/ezgmaplocation-ls-extension": "~5.3",
        "ezsystems/ezie-ls": "~5.3",
        "ezsystems/ezmbpaex-ls": "~5.3",
        "ezsystems/ezmultiupload-ls": "~5.3",
        "ezsystems/ezodf-ls": "~5.3",
        "ezsystems/ezprestapiprovider-ls": "~5.3",
        "ezsystems/ezscriptmonitor-ls": "~5.3",
        "ezsystems/ezsi-ls": "~5.3",
        "ezsystems/ezstarrating-ls-extension": "~5.3",
        "ezsystems/ezwt-ls-extension": "~5.3",
        "ezsystems/ezfind-ls": "~5.3|>=2014.05",
```