Merge #13955: gitian: bump descriptors for (0.)18

263b3777e7 gitian: bump descriptors for (0.)18 (fanquake)

Pull request description:

Tree-SHA512: 6faeac38fb943c0745a0cd8363d5977be658cff75ffc3db262d87518f72a4b435e51b6be52702619c33653e733952673a66aa0f8c5da24f0ea10d164369aecf6

contrib/gitian-descriptors/gitian-linux.yml

@@ -1,5 +1,5 @@
 ---
-name: "bitcoin-linux-0.17"
+name: "bitcoin-linux-0.18"
 enable_cache: true
 suites:
 - "bionic"

contrib/gitian-descriptors/gitian-osx.yml

@@ -1,5 +1,5 @@
 ---
-name: "bitcoin-osx-0.17"
+name: "bitcoin-osx-0.18"
 enable_cache: true
 suites:
 - "bionic"

contrib/gitian-descriptors/gitian-win.yml

@@ -1,5 +1,5 @@
 ---
-name: "bitcoin-win-0.17"
+name: "bitcoin-win-0.18"
 enable_cache: true
 suites:
 - "bionic"