Add Payback Loyalty Program (#6429)

* Add Payback Loyalty Program

* Update payback.de.json

Remove empty tag

* Update entries/p/payback.de.json
Co-authored-by: Carlgo11 <Carlgo11@users.noreply.github.com>

* Update img/p/payback.de.svg
Co-authored-by: Carlgo11 <Carlgo11@users.noreply.github.com>

* Update payback.de.json

* Update payback.de.json

Add custom-software tag
Co-authored-by: Carlgo11 <Carlgo11@users.noreply.github.com>

entries/p/payback.de.json

+{
+  "Payback": {
+    "domain": "payback.de",
+    "tfa": [
+      "custom-software"
+    ],
+    "custom-software": [
+      "Payback App"
+    ],
+    "documentation": "https://www.payback.de/faq/2-schritt-verifizierung",
+    "keywords": [
+      "other"
+    ],
+    "regions": [
+      "de"
+    ]
+  }
+}

img/p/payback.de.svg

+<svg xmlns="http://www.w3.org/2000/svg" style="fill:none;background:#0046aaff;stroke-width:1.5;stroke:#fff" viewBox="0 0 115.5 115.5"><g id="b"><circle id="a" cx="21.5" cy="21.5" r="12.9"/><use x="35.7" href="#a"/><use x="71.3" fill="#fff" href="#a"/></g><use y="35.7" href="#b"/><use x="35.7" y="35.7" fill="#fff" href="#a"/><use y="71.3" href="#b"/></svg>
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