c-api: add Wasmtime version macros to wasmtime.h (#5651)

* Add several `WASMTIME_VERSION_*` macros to `wasmtime.h`.
* Update `scripts/publish.rs`
  * To set these macros as per the new version in `./Cargo.toml` during
    `./publish bump`.
  * To verify the macros match the version in `./Cargo.toml` during
    `./publish verify`.

Fix #5635

crates/c-api/include/wasmtime.h

@@ -196,6 +196,23 @@
 #include <wasmtime/trap.h>
 #include <wasmtime/val.h>
 
+/**
+ * \brief Wasmtime version string.
+ */
+#define WASMTIME_VERSION "6.0.0"
+/**
+ * \brief Wasmtime major version number.
+ */
+#define WASMTIME_VERSION_MAJOR 6
+/**
+ * \brief Wasmtime minor version number.
+ */
+#define WASMTIME_VERSION_MINOR 0
+/**
+ * \brief Wasmtime patch version number.
+ */
+#define WASMTIME_VERSION_PATCH 0
+
 #ifdef __cplusplus
 extern "C" {
 #endif