[chore] drop lingva engine / lingva-translate no onger maintained

The lingva-translate seems to be dead. Even the instances specified in the
README [1] have not been updated for 12 months and no longer correspond to the
current status, for example https://translate.projectsegfau.lt/ has already
switched to Mozhi.

The official instance lingva.ml keeps failing [2] and seems to me to have a
different interface than we have implemented in the engine.  Somehow it all
seems to be a bit of a mess, I can't think of any other solution than to take
the engine out of SearXNG for the time being (unfortunately).

[1] https://github.com/thedaviddelta/lingva-translate/blob/main/README.md#instances
[2] https://github.com/thedaviddelta/lingva-translate/issues/184#issuecomment-2461363898

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/engines/lingva.py

@@ -1,65 +0,0 @@
-# SPDX-License-Identifier: AGPL-3.0-or-later
-"""Lingva (alternative Google Translate frontend)"""
-
-from json import loads
-
-about = {
-    "website": 'https://lingva.ml',
-    "wikidata_id": None,
-    "official_api_documentation": 'https://github.com/thedaviddelta/lingva-translate#public-apis',
-    "use_official_api": True,
-    "require_api_key": False,
-    "results": 'JSON',
-}
-
-engine_type = 'online_dictionary'
-categories = ['general', 'translate']
-
-url = "https://lingva.thedaviddelta.com"
-search_url = "{url}/api/v1/{from_lang}/{to_lang}/{query}"
-
-
-def request(_query, params):
-    params['url'] = search_url.format(
-        url=url, from_lang=params['from_lang'][1], to_lang=params['to_lang'][1], query=params['query']
-    )
-    return params
-
-
-def response(resp):
-    results = []
-
-    result = loads(resp.text)
-    info = result["info"]
-    from_to_prefix = "%s-%s " % (resp.search_params['from_lang'][1], resp.search_params['to_lang'][1])
-
-    if "typo" in info:
-        results.append({"suggestion": from_to_prefix + info["typo"]})
-
-    if 'definitions' in info:  # pylint: disable=too-many-nested-blocks
-        for definition in info['definitions']:
-            if 'list' in definition:
-                for item in definition['list']:
-                    if 'synonyms' in item:
-                        for synonym in item['synonyms']:
-                            results.append({"suggestion": from_to_prefix + synonym})
-
-    infobox = ""
-
-    for translation in info["extraTranslations"]:
-        for word in translation["list"]:
-            infobox += f"<dl><dt>{word['word']}</dt>"
-
-            for meaning in word["meanings"]:
-                infobox += f"<dd>{meaning}</dd>"
-
-            infobox += "</dl>"
-
-    results.append(
-        {
-            'infobox': result["translation"],
-            'content': infobox,
-        }
-    )
-
-    return results

searx/settings.yml

@@ -1121,12 +1121,6 @@ engines:
     shortcut: lt
     disabled: true
 
-  - name: lingva
-    engine: lingva
-    shortcut: lv
-    # set lingva instance in url, by default it will use the official instance
-    # url: https://lingva.thedaviddelta.com
-
   - name: lobste.rs
     engine: xpath
     search_url: https://lobste.rs/search?q={query}&what=stories&order=relevance