replace 2-element f-strings with simple '+' concatenations

Python's 'ast' module and its 'NodeVisitor' class
were incredibly helpful in identifying these

gallery_dl/extractor/bellazon.py

@@ -24,7 +24,7 @@ class BellazonExtractor(Extractor):
     archive_fmt = "{post[id]}/{id}_{filename}"
 
     def items(self):
-        native = (f"{self.root}/", f"{self.root[6:]}/")
+        native = (self.root + "/", self.root[6:] + "/")
         extract_urls = text.re(
             r'(?s)<('
             r'(?:video .*?<source [^>]*?src|a [^>]*?href)="([^"]+).*?</a>'
@@ -82,7 +82,7 @@ class BellazonExtractor(Extractor):
                         dc["extension"] = text.ext_from_url(url)
 
                     if url[0] == "/":
-                        url = f"https:{url}"
+                        url = "https:" + url
                     yield Message.Url, url, dc
 
                 else:
@@ -91,10 +91,10 @@ class BellazonExtractor(Extractor):
                     yield Message.Queue, url, data
 
     def _pagination(self, base, pnum=None):
-        base = f"{self.root}{base}"
+        base = self.root + base
 
         if pnum is None:
-            url = f"{base}/"
+            url = base + "/"
             pnum = 1
         else:
             url = f"{base}/page/{pnum}/"
@@ -112,7 +112,7 @@ class BellazonExtractor(Extractor):
             url = f"{base}/page/{pnum}/"
 
     def _pagination_reverse(self, base, pnum=None):
-        base = f"{self.root}{base}"
+        base = self.root + base
 
         url = f"{base}/page/{'9999' if pnum is None else pnum}/"
         with self.request(url) as response:
@@ -127,7 +127,7 @@ class BellazonExtractor(Extractor):
             if pnum > 1:
                 url = f"{base}/page/{pnum}/"
             elif pnum == 1:
-                url = f"{base}/"
+                url = base + "/"
             else:
                 return
 
@@ -198,9 +198,9 @@ class BellazonPostExtractor(BellazonExtractor):
 
     def posts(self):
         path, post_id = self.groups
-        page = self.request(f"{self.root}{path}").text
+        page = self.request(self.root + path).text
 
-        pos = page.find(f'id="elComment_{post_id}')
+        pos = page.find('id="elComment_' + post_id)
         if pos < 0:
             raise exception.NotFoundError("post")
         html = text.extract(page, "<article ", "</article>", pos-100)[0]