[enh] Add Petalsearch.com engine (xpath) (#2897)

* [enh] Add Petalsearch.com engine (xpath)

Upstream example query:
https://petalsearch.com/search?query=Felis%20lynx%20Linnaeus&sregion=de&pn=1

* Fix Petalsearch title_xpath

Fixes the title_xpath from Petalsearch which got changed in the meantime.

searx/settings.yml

@@ -1377,6 +1377,24 @@ engines:
       require_api_key: false
       results: html
 
+    shortcut : petal
+    engine : xpath
+    paging : True
+    search_url : https://petalsearch.com/search?query={query}&pn={pageno}
+    title_xpath : //div[@class="card-title"]/span
+    url_xpath : //a[@class="card-main"]/@href
+    content_xpath : //div[@class="webpage-text"]
+    page_size : 12
+    categories : general
+    timeout : 4.0
+    disabled : True
+    about:
+      website: https://petalsearch.com
+      wikidata_id: #
+      use_official_api: false
+      require_api_key: false
+      results: HTML
+
   - name : ask
     shortcut : ask
     engine : xpath