Update the costs structure of Saxo Bank

Starting from May 13th, Saxo will apply a new fee structure to their products.
See https://www.home.saxo/-/media/documents/regional/nl/pricing-unified.pdf?revision=db393ec4-e48a-4be2-a5e4-7751670cd203.

The transaction fees for ETFs are the ones for Bronze accounts. The account type
(Bronze/Silver/Gold) is determined by Saxo based on the size of the account, but
this is not yet supported by our simulation.
This means that in reality transaction fees will be lower ones the account
becomes bigger than € 200,000.
See https://www.home.saxo/nl-nl/campaigns/invest-for-less.

Because all mutual funds listed with Saxo on this website are available for
AutoInvest (according to the data provided by @teunlielu in
#49), the
transaction costs for mutual funds have been set to 0.
See https://www.home.saxo/nl-nl/products/autoinvest for more about AutoInvest.

data/brokers.json

@@ -92,24 +92,20 @@
     {
         "name": "Saxo Bank",
         "logo": "saxo.png",
-        "product": "Zelf Beleggen Green",
+        "product": "Zelf Beleggen",
         "serviceFee": {
-            "base": 3.5,
             "percentage": 0.01,
-            "maximum": 48.5
+            "maximum": 40
         },
         "serviceFeeFrequency": "monthly",
-        "mutualFundTransactionFee": {
-            "percentage": 0.15,
-            "minimum": 8,
-            "maximum": 150
-        },
+        "mutualFundTransactionFee": 0,
         "etfTransactionFee": {
-            "percentage": 0.1,
-            "minimum": 6,
-            "maximum": 150
+            "percentage": 0.08,
+            "minimum": 2,
+            "maximum": 150,
+            "_comment": "Based on the Bronze account, the fee is lower for accounts with higher equity."
         },
-        "costOverview": "https://www.home.saxo/-/media/documents/regional/nl/Pricing-Standard.pdf",
+        "costOverview": "https://www.home.saxo/-/media/documents/regional/nl/pricing-unified.pdf?revision=db393ec4-e48a-4be2-a5e4-7751670cd203",
         "website": "https://www.home.saxo/nl-nl"
     },
     {