Only build ghc96 in CI (#7373)

Author: zeme-wana

nix/outputs.nix

@@ -112,7 +112,7 @@ let
     { profiled = mkShell project.projectVariants.ghc96-profiled; } //
     { metatheory-jailbreak = metatheory-jailbreak-shell; };
 
-  nested-ci-jobs = {
+  full-nested-ci-jobs = {
     "x86_64-linux" =
       (project-variants-hydra-jobs) //
       (windows-hydra-jobs) //
@@ -131,9 +131,30 @@ let
       { required = hydra-required-job; };
   };
 
-  flattened-ci-jobs = utils.flattenDerivationTree ":" nested-ci-jobs;
+  small-nested-ci-jobs = {
+    "x86_64-linux" =
+      (windows-hydra-jobs) //
+      (packages) //
+      { ghc96 = project-variants-hydra-jobs.ghc96; } //
+      { devShells.default = non-profiled-shells.default; } //
+      { devShells.metatheory-jailbreak = metatheory-jailbreak-shell; } //
+      { required = hydra-required-job; };
+    "x86_64-darwin" =
+      { ghc96 = project-variants-hydra-jobs.ghc96; } //
+      { devShells.default = non-profiled-shells.default; } //
+      { devShells.metatheory-jailbreak = metatheory-jailbreak-shell; } //
+      { required = hydra-required-job; };
+    "aarch64-linux" =
+      { };
+    "aarch64-darwin" =
+      { devShells.default = non-profiled-shells.default; } //
+      { devShells.metatheory-jailbreak = metatheory-jailbreak-shell; } //
+      { required = hydra-required-job; };
+  };
+
+  flattened-ci-jobs = utils.flattenDerivationTree ":" small-nested-ci-jobs;
 
-  ciJobs = utils.flattenDerivationTree ":" nested-ci-jobs.${system};
+  ciJobs = utils.flattenDerivationTree ":" small-nested-ci-jobs.${system};
 
   checks = ciJobs;
 
@@ -151,7 +172,8 @@ let
     inherit static-haskell-packages;
     inherit exposed-haskell-packages;
     inherit flattened-ci-jobs;
-    inherit nested-ci-jobs;
+    inherit full-nested-ci-jobs;
+    inherit small-nested-ci-jobs;
     inherit metatheory;
     inherit project-coverage-report;
   };