fix: get pgai working on i386 (#284)

Dockerfile

@@ -78,7 +78,16 @@ RUN set -ex; \
         cd /build/pgai; \
         # note: this is a hack. pyarrow will be built from source, so must be pinned to this arrow version \
         echo pyarrow==$(pkg-config --modversion arrow) >> ./projects/extension/requirements.txt; \
+        if [ "$TARGETARCH" == "386" ]; then \
+            # note: pinned because pandas 2.2.0-2.2.3 on i386 is affected by https://github.com/pandas-dev/pandas/issues/59905 \
+            echo pandas==2.1.4 >> ./projects/extension/requirements.txt; \
+            # note: no prebuilt binaries for pillow on i386 \
+            apk add --no-cache --virtual .pgai-deps-386 \
+                jpeg-dev \
+                zlib-dev; \
+        fi; \
         PG_BIN="/usr/local/bin" PG_MAJOR=${PG_MAJOR_VERSION} ./projects/extension/build.py install; \
+        if [ "$TARGETARCH" == "386" ]; then apk del .pgai-deps-386; fi; \
         apk del .pgai-deps; \
     fi