doc: Remove my key from SECURITY.md

As I am no longer on the `[email protected]` alias, there is no
point in asking people to GPG-encrypt to me. Remove it.

Tree-SHA512: f15640b741b908b162acf149ab27dae149fc917c15fbabf8dd9aff7bc6afb9e8b2ae956f9a0f8fbe1f05f40a48215becc1efda90a2e9c1105559cdeafb073060

Author: laanwj

SECURITY.md

@@ -13,7 +13,6 @@ The following keys may be used to communicate sensitive information to developer
 
 | Name | Fingerprint |
 |------|-------------|
-| Wladimir van der Laan | 71A3 B167 3540 5025 D447  E8F2 7481 0B01 2346 C9A6 |
 | Pieter Wuille | 133E AC17 9436 F14A 5CF1  B794 860F EB80 4E66 9320 |
 | Michael Ford | E777 299F C265 DD04 7930  70EB 944D 35F9 AC3D B76A |