Add feedback for markov bot reply chance

This will just send a message to the user who just updated their markov
reply chance with the final value it was set to, so there are no
surprises.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

plugins/markov.py

@@ -236,11 +236,20 @@ class Markov(Plugin):
                     self.send_to(conn, channel, f"{who.nick}: {message}")
             case ["chance", chance]:
                 chain = self.get_chain(channel, who.nick)
-                reply_chance = float(chance)
+                try:
+                    reply_chance = float(chance)
+                except ValueError:
+                    log.error("Couldn't parse %r as a float", chance)
+                    return
                 if not math.isnan(reply_chance):
                     chain.reply_chance = min(
                         max(float(reply_chance), 0.0), self.reply_chance
                     )
+                self.send_to(
+                    conn,
+                    channel,
+                    f"{who.nick}: reply chance set to {chain.reply_chance}",
+                )
             case _:
                 # command not recognized
                 pass