Allow RSA 2047 bit keys (#20272)

Unfortunately it appears that 2048 bit RSA keys can occasionally be created in such
a way that they appear to have 2047 bit length. This PR simply changes our defaults to
allow these.

Fix #20249

Signed-off-by: Andrew Thornton <art27@cantab.net>

custom/conf/app.example.ini

@@ -1231,7 +1231,7 @@ PATH =
 ;; Define allowed algorithms and their minimum key length (use -1 to disable a type)
 ;ED25519 = 256
 ;ECDSA = 256
-;RSA = 2048
+;RSA = 2047 ; we allow 2047 here because an otherwise valid 2048 bit RSA key can be reported as having 2047 bit length
 ;DSA = -1 ; set to 1024 to switch on
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;