fix(ci): replace fake goto-bus-stop/setup-zig SHA pin (2 sites)

The pin `goto-bus-stop/setup-zig@7ab2955eb728f5440978d7b4f723a50dea1f3608`
is fabricated (`gh api repos/goto-bus-stop/setup-zig/commits/7ab2955... -> 422`).
The fake SHA's first 16 hex chars happen to collide with v2.2.0's real SHA
`7ab2955eb728f5440978d5824358023be3a2802d` but the rest is fabricated.

Affected: 2 sites in .github/workflows/e2e.yml.

Replaced with the verified v2.2.1 pin
`abea47f85e598557f500fa1fd2ab7464fcb39406`.

Provenance: propagated from rsr-template-repo#81 (merged); discovered while
wiring CI for snifs (hyperpolymath/snifs#30); 1 of 3 fan-out PRs alongside
odds-and-sods-package-manager#39 and (incoming) proven-servers.

Author: hyperpolymath

.github/workflows/e2e.yml

@@ -43,7 +43,7 @@ jobs:
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5  # v4
 
       - name: Install Zig
-        uses: goto-bus-stop/setup-zig@7ab2955eb728f5440978d7b4f723a50dea1f3608  # v2
+        uses: goto-bus-stop/setup-zig@abea47f85e598557f500fa1fd2ab7464fcb39406  # v2.2.1
         with:
           version: 0.15.0
 
@@ -154,7 +154,7 @@ jobs:
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5  # v4
 
       - name: Install Zig
-        uses: goto-bus-stop/setup-zig@7ab2955eb728f5440978d7b4f723a50dea1f3608  # v2
+        uses: goto-bus-stop/setup-zig@abea47f85e598557f500fa1fd2ab7464fcb39406  # v2.2.1
         with:
           version: 0.15.0