chore: downgrade toolchain to 1.86 on all versions

This is just because managing both 1.86 and 1.88 is really annoying, so
it's better to just be unified. There's no real point to using 1.88
besides more clippy warnings, which are already impeding my work right
now. So we're downgrading.

.github/workflows/build.yaml

@@ -14,19 +14,19 @@ jobs:
           - os: ubuntu-latest
             target: x86_64-unknown-linux-gnu
             artifact_name: pacman
-            toolchain: 1.88.0
+            toolchain: 1.86.0
           - os: macos-13
             target: x86_64-apple-darwin
             artifact_name: pacman
-            toolchain: 1.88.0
+            toolchain: 1.86.0
           - os: macos-latest
             target: aarch64-apple-darwin
             artifact_name: pacman
-            toolchain: 1.88.0
+            toolchain: 1.86.0
           - os: windows-latest
             target: x86_64-pc-windows-gnu
             artifact_name: pacman.exe
-            toolchain: 1.88.0
+            toolchain: 1.86.0
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout

.github/workflows/tests.yaml

@@ -4,7 +4,7 @@ on: ["push", "pull_request"]
 
 env:
   CARGO_TERM_COLOR: always
-  RUST_TOOLCHAIN: 1.88.0
+  RUST_TOOLCHAIN: 1.86.0
 
 jobs:
   test:

rust-toolchain.toml

@@ -0,0 +1,2 @@
+[toolchain]
+channel = "1.86.0"