build: automate version resolution in build.zig

Removes manual git flags from CI and build scripts.
Versioning is now automatically derived from git and build.zig.zon.

With this PR, we follow https://semver.org/
Logic:

1. Read the version from build.zig.zon
2. If it doesn't have a `.pre` field (i.e. dev/alpha/beta) it will use that
3. Otherwise it will get the info from git: hash and number of commits since last `.0` version
4. Then build the version: `0.3.0-dev.1493+0896edc3`

Note that, since the latest stable version is `0.2.6`.
The convention is to use `0.3.0-dev`, as:
- `0.2.6` < `0.3.0.dev` < `0.3.0`

build.zig.zon

@@ -1,6 +1,6 @@
 .{
     .name = .browser,
-    .version = "0.0.0",
+    .version = "0.3.0-dev",
     .fingerprint = 0xda130f3af836cea0, // Changing this has security and trust implications.
     .minimum_zig_version = "0.15.2",
     .dependencies = .{