Upgrade to support Postgres 17 (#26)

Upgrade to pgrx v0.12.6 and supabase-wrappers v0.1.20 to do so. Fix the
updated argument to `ForeignDataWrapper::new()` and update all other
dependencies. Add the `src/bin` placeholder pgrx v0.12.x requires and
update the version to v0.2.1.

Author: theory

.github/workflows/extension_ci.yml

@@ -21,7 +21,7 @@ jobs:
     name: Run linters
     runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Install Rust minimal nightly with clippy and rustfmt
         uses: actions-rs/toolchain@v1
         with:
@@ -49,7 +49,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        pg: [ 14, 15, 16 ]
+        pg: [ 14, 15, 16, 17 ]
     steps:
       - uses: actions/checkout@v4
       - name: Install Rust stable toolchain

.github/workflows/pages-deployment.yml

@@ -8,7 +8,7 @@ jobs:
   deploy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: actions/setup-python@v2
         with:
           python-version: 3.x