Disable FreeBSD CI for now. (#530)

FreeBSD CI has been broken for some time with this error

```
[4/4] Extracting curl-7.87.0_1: .......... done
curl https://sh.rustup.rs -sSf --output rustup.sh
ld-elf.so.1: /usr/local/lib/libcurl.so.4: Undefined symbol "nghttp2_option_set_no_rfc9113_leading_and_trailing_ws_validation"
```

Comment it out for now.

Author: sunfishcode

.cirrus.yml

@@ -1,16 +1,22 @@
 # Implementation derived from `.cirrus.yml` in Rust's libc bindings
 # at revision 7f4774e76bd5cb9ccb7140d71ef9be9c16009cdf.
 
-task:
-  name: stable x86_64-unknown-freebsd-13
-  freebsd_instance:
-    image_family: freebsd-13-0-snap
-  setup_script:
-    - pkg install -y curl
-    - curl https://sh.rustup.rs -sSf --output rustup.sh
-    - sh rustup.sh --default-toolchain stable -y --profile=minimal
-    - . $HOME/.cargo/env
-    - rustup default stable
-  test_script:
-    - . $HOME/.cargo/env
-    - cargo test --workspace --features=all-apis
+# Disable FreeBSD testing for now, as we currently hit this error:
+#
+# [4/4] Extracting curl-7.87.0_1: .......... done
+# curl https://sh.rustup.rs -sSf --output rustup.sh
+# ld-elf.so.1: /usr/local/lib/libcurl.so.4: Undefined symbol "nghttp2_option_set_no_rfc9113_leading_and_trailing_ws_validation"
+
+#task:
+#  name: stable x86_64-unknown-freebsd-13
+#  freebsd_instance:
+#    image_family: freebsd-13-0-snap
+#  setup_script:
+#    - pkg install -y curl
+#    - curl https://sh.rustup.rs -sSf --output rustup.sh
+#    - sh rustup.sh --default-toolchain stable -y --profile=minimal
+#    - . $HOME/.cargo/env
+#    - rustup default stable
+#  test_script:
+#    - . $HOME/.cargo/env
+#    - cargo test --workspace --features=all-apis