[PROF-11524] Bump libdatadog version to 18.1.0 in preparation for release (#1075)

**What does this PR do?**

This PR bumps the libdatadog version from 18.0.0 to 18.1.0 in
preparation for release.

We're going from v18.0 to v18.1 as I'm not aware of any
backwards-incompatible changes being merged to master.

**Motivation:**

Ruby has been stuck on an old libdatadog release due to a few API
changes, and I want to finally move it to latest libdatadog.

**Additional Notes:**

I did a diff of the v18.0 to v18.1 headers to validate there's no
backwards-incompatible changes using the `difft` tool:

```
library-config.h --- C++
No changes.

blazesym.h --- C++
No changes.

profiling.h --- C++
No changes.

crashtracker.h --- 1/2 --- C++
57 57 extern "C" {
58 58 #endif // __cplusplus
.. 59
.. 60 /**
.. 61  * Disables the crashtracker.
.. 62  * Note that this does not restore the old signal handlers, but rather turns crash-tracking into a
.. 63  * no-op, and then chains the old handlers.  This means that handlers registered after the
.. 64  * crashtracker will continue to work as expected.
.. 65  *
.. 66  * # Preconditions
.. 67  *   None
.. 68  * # Safety
.. 69  *   None
.. 70  * # Atomicity
.. 71  *   This function is atomic and idempotent.  Calling it multiple times is allowed.
.. 72  */
.. 73 DDOG_CHECK_RETURN struct ddog_VoidResult ddog_crasht_disable(void);
.. 74
.. 75 /**
.. 76  * Enables the crashtracker, if it had been previously disabled.
.. 77  * If crashtracking has not been initialized, this function will have no effect.
.. 78  *
.. 79  * # Preconditions
.. 80  *   None
.. 81  * # Safety
.. 82  *   None
.. 83  * # Atomicity
.. 84  *   This function is atomic and idempotent.  Calling it multiple times is allowed.
.. 85  */
.. 86 DDOG_CHECK_RETURN struct ddog_VoidResult ddog_crasht_enable(void);
59 87
60 88 /**
61 89  * Reinitialize the crash-tracking infrastructure after a fork.

crashtracker.h --- 2/2 --- C++
 98 126                                         struct ddog_crasht_ReceiverConfig receiver_config,
 99 127                                         struct ddog_crasht_Metadata metadata);
 .. 128
 .. 129 /**
 .. 130  * Reconfigure the crashtracker and re-enables it.
 .. 131  * If the crashtracker has not been initialized, this function will have no effect.
 .. 132  *
 .. 133  * # Preconditions
 .. 134  *   None.
 .. 135  * # Safety
 .. 136  *   Crash-tracking functions are not reentrant.
 .. 137  *   No other crash-handler functions should be called concurrently.
 .. 138  * # Atomicity
 .. 139  *   This function is not atomic. A crash during its execution may lead to
 .. 140  *   unexpected crash-handling behaviour.
 .. 141  */
 .. 142 DDOG_CHECK_RETURN
 .. 143 struct ddog_VoidResult ddog_crasht_reconfigure(struct ddog_crasht_Config config,
 .. 144                                                struct ddog_crasht_ReceiverConfig receiver_config,
 .. 145                                                struct ddog_crasht_Metadata metadata);
100 146
101 147 /**
102 148  * Initialize the crash-tracking infrastructure without launching the receiver.

data-pipeline.h --- C++
No changes.

telemetry.h --- C++
No changes.

common.h --- C++
No changes.
```

**How to test the change?**

I've tested the libdatadog 18.1 release locally using the Ruby test
suite and DataDog/dd-trace-rb#4577 .

Author: ivoanjo

Cargo.lock

@@ -58,7 +58,7 @@ resolver = "2"
 [workspace.package]
 rust-version = "1.78.0"
 edition = "2021"
-version = "18.0.0"
+version = "18.1.0"
 license = "Apache-2.0"
 
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