Replace expired GPG public key which is used to upgrade to enterprise (#20075)

Signed-off-by: Mustafa Kara <mustafa.kara@mattermost.com>

services/upgrader/upgrader_linux.go

@@ -36,14 +36,14 @@ fl6WltLrepiExTp6NMZ50k+Em4JGM6CWBMo22ucy0jYjZXO5hEGb3o6NGiG+Dx2z
 b2J78LksCKGsSrn0F1rLJeA933bFL4g9ozv9asBlzmpgG77ESg6YE1N/Rh7WDzVA
 prIR0MuB5JjElASw5LDVxDV6RZsxEVQr7ETLABEBAAG0KU1hdHRlcm1vc3QgQnVp
 bGQgPGRldi1vcHNAbWF0dGVybW9zdC5jb20+iQFUBBMBCAA+AhsDBQsJCAcCBhUI
-CQoLAgQWAgMBAh4BAheAFiEEobMdRvDzoQsCzy1E+PLDF0R3SygFAl6HYr0FCQlw
-hqEACgkQ+PLDF0R3SyheNQgAnkiT2vFMCtU5FmC16HVYXzDpYMtdCQPh/gmeEkiI
-80rFRg/cn6f0BNnaTfDu6r6cepmhLNpDAowjQ7uBnv8fL2dzCydIGFv2r7FfmcOJ
-zhEQ3zXPwP6mYlxPCCgxAozsLv9Yv41KGCHIlzYwkAazc0BhpAW/h8L3VGkE+b+g
-x6lKVoufm4rKnT49Dgly6fVOxuR/BqZo87B5jksV3izLTHt5hiY8Pc5GW8WwO/tr
-pNAw+6HRXq1Dr/JRz5PIOr5KP5tVLBed4IteZ1xaTRd4++07ZbiZjhXY8WKpVp3y
-iN7Om24jQpxbJI9+KKJ3+yhcwhr8/PJ8ZVuhJo3BNv1PcQ==
-=9Qk8
+CQoLAgQWAgMBAh4BAheAFiEEobMdRvDzoQsCzy1E+PLDF0R3SygFAmJOqWgFCQ03
+zUwACgkQ+PLDF0R3Syg/rQf8D5BgvVFnGuHDYNu2eiasZdfxmuhg1C7JGSLHqoCT
+SB/0SLLQyMeHsJLye/gbo3yhK8G9XYOm+obGF+NDxB0LtRaPv5Q6pIQYt88ZxOGA
+Kh6RG2DjYA5j410wYrN0mNzhudqnS2yZdyq215nEr7Z6l1T7L9OPcz0u0mF9RraQ
+nawzxbxc8mPuC5tMLTedViSkTYLgMY12TCSYhykseUIGrl/FBfMbmKwBHM52SZJh
+maBevuNymlFbODTciyE9Q7mJHkaamGKTXaa3Enlcf16oSoemawSBJuspaS0sZOW8
+dgi5l3V5YvfFvSk45axiZbnGYfN81G5mkSGAENSGSKVtMA==
+=kkvg
 -----END PGP PUBLIC KEY BLOCK-----`
 
 var upgradePercentage int64