chore: drop Python 3.5 (#3719)

* chore: drop Python 3.5 support

* chore: more fstrings with flynt's help

* ci: drop Python 3.5

* chore: bump dependency versions

* docs: touch up py::args

* tests: remove deprecation warning

* Ban smartquotes

* Very minor tweaks (by-product of reviewing PR #3719).

Co-authored-by: Aaron Gokaslan <skylion.aaron@gmail.com>
Co-authored-by: Ralf W. Grosse-Kunstleve <rwgk@google.com>

tools/libsize.py

@@ -13,7 +13,7 @@ lib = sys.argv[1]
 save = sys.argv[2]
 
 if not os.path.exists(lib):
-    sys.exit("Error: requested file ({}) does not exist".format(lib))
+    sys.exit(f"Error: requested file ({lib}) does not exist")
 
 libsize = os.path.getsize(lib)
 
@@ -28,7 +28,7 @@ if os.path.exists(save):
         if change == 0:
             print(" (no change)")
         else:
-            print(" (change of {:+} bytes = {:+.2%})".format(change, change / oldsize))
+            print(f" (change of {change:+} bytes = {change / oldsize:+.2%})")
 else:
     print()