ci: Don't build if there are no code changes

Reconfigured the build & lint workflows, so that the source is only
compiled if there are changes committed to files that might alter the
output.

Signed-off-by: Gergely Nagy <me@gergo.csillger.hu>

.forgejo/workflows/build.yaml

@@ -9,6 +9,13 @@ on:
   push:
     branches:
       - 'main'
+    paths:
+      - '.forgejo/workflows/build.yaml'
+      - 'flake.nix'
+      - 'flake.lock'
+      - 'nix/**'
+      - 'Cargo.*'
+      - 'src/**'
 
 jobs:
   build:
@@ -48,3 +55,19 @@ jobs:
       - name: publish
         run:
           docker push git.madhouse-project.org/algernon/iocaine:latest
+
+  clippy:
+    runs-on: nixos-latest
+    steps:
+      - name: checkout
+        uses: actions/checkout@v4
+
+      - name: setup magic attic cache
+        uses: actions/magic-attic-cache@main
+        with:
+          ATTIC_TOKEN: ${{ secrets.ATTIC_TOKEN }}
+
+      - name: clippy
+        uses: actions/nix/develop@main
+        with:
+          run: cargo clippy

.forgejo/workflows/lint.yaml

@@ -26,19 +26,3 @@ jobs:
         uses: actions/nix/develop@main
         with:
           run: treefmt --fail-on-change
-
-  clippy:
-    runs-on: nixos-latest
-    steps:
-      - name: checkout
-        uses: actions/checkout@v4
-
-      - name: setup magic attic cache
-        uses: actions/magic-attic-cache@main
-        with:
-          ATTIC_TOKEN: ${{ secrets.ATTIC_TOKEN }}
-
-      - name: clippy
-        uses: actions/nix/develop@main
-        with:
-          run: cargo clippy