feat(proxies): ✨ Add SurfsharkVPN support

Original code by @p0llux12 - Discord

- Introduced `SurfsharkVPN` class for proxy service integration.
- Updated configuration to include `surfsharkvpn` in proxy providers.
- Removed legacy `nordvpn` configuration from YAML.
- Enhanced `dl.py` and `search.py` to utilize `SurfsharkVPN`.

unshackle/commands/dl.py

@@ -48,7 +48,7 @@ from unshackle.core.constants import DOWNLOAD_LICENCE_ONLY, AnyTrack, context_se
 from unshackle.core.credential import Credential
 from unshackle.core.drm import DRM_T, PlayReady, Widevine
 from unshackle.core.events import events
-from unshackle.core.proxies import Basic, Hola, NordVPN
+from unshackle.core.proxies import Basic, Hola, NordVPN, SurfsharkVPN
 from unshackle.core.service import Service
 from unshackle.core.services import Services
 from unshackle.core.titles import Movie, Movies, Series, Song, Title_T
@@ -309,6 +309,8 @@ class dl:
                     self.proxy_providers.append(Basic(**config.proxy_providers["basic"]))
                 if config.proxy_providers.get("nordvpn"):
                     self.proxy_providers.append(NordVPN(**config.proxy_providers["nordvpn"]))
+                if config.proxy_providers.get("surfsharkvpn"):
+                    self.proxy_providers.append(SurfsharkVPN(**config.proxy_providers["surfsharkvpn"]))
                 if binaries.HolaProxy:
                     self.proxy_providers.append(Hola())
                 for proxy_provider in self.proxy_providers: