Correcting the cabal versions to match newer ghc versions.

Author: recursion-ninja

.travis.yml

@@ -38,15 +38,15 @@ matrix:
     - env: CABALVER=1.24 GHCVER=8.0.1
       compiler: ": #GHC 8.0.1"
       addons: {apt: {packages: [cabal-install-1.24,ghc-8.0.1], sources: [hvr-ghc]}}
-    - env: CABALVER=1.24 GHCVER=8.2.2
+    - env: CABALVER=2.0 GHCVER=8.2.2
       compiler: ": #GHC 8.2.2"
-      addons: {apt: {packages: [cabal-install-1.24,ghc-8.2.2], sources: [hvr-ghc]}}
-    - env: CABALVER=1.24 GHCVER=8.4.3
+      addons: {apt: {packages: [cabal-install-2.0,ghc-8.2.2], sources: [hvr-ghc]}}
+    - env: CABALVER=2.2 GHCVER=8.4.3
       compiler: ": #GHC 8.4.3"
-      addons: {apt: {packages: [cabal-install-1.24,ghc-8.4.3], sources: [hvr-ghc]}}
-    - env: CABALVER=1.24 GHCVER=8.6.1
+      addons: {apt: {packages: [cabal-install-2.2,ghc-8.4.3], sources: [hvr-ghc]}}
+    - env: CABALVER=2.4 GHCVER=8.6.1
       compiler: ": #GHC 8.6.1"
-      addons: {apt: {packages: [cabal-install-1.24,ghc-8.6.1], sources: [hvr-ghc]}}
+      addons: {apt: {packages: [cabal-install-2.4,ghc-8.6.1], sources: [hvr-ghc]}}
     - env: CABALVER=head GHCVER=head
       compiler: ": #GHC head"
       addons: {apt: {packages: [cabal-install-head,ghc-head], sources: [hvr-ghc]}}